I Despise Family Drama.

Your husband needs to deal with his family and I agree with not wanting her to pick up your children any longer, because if you do and she becomes upset with you again, she's going to play the same card.

I love my family too, but last holiday season there was so much drama....I'm loving them from a distance. I do not intend to spend Thanksgiving or Christmas with them this year. I'm starting some of my own traditions.

Make your apologies to her for your wrongs. And in the future, remember that you can love her, care for her, but not place her in a position of trust or responsibility over the things important to you - this may include your child, or even your opinion. And that is perfectly okay; no reason for feeling guilty, giving her any explaination, ect....

You've gotten some good advice here -- especially about its being your husband's role to talk to her; she's his sister and it's his responsibility to deal with her first -- but I would just add: Hating family drama is great, but if you "hate" it to the point that you are totally nonconfrontational and don't respond, you get the result that you had here: You bottle things up until you fire off a rude e-mail and an explosion results, and things are far worse. Had you not shrugged off the comments and not ignored the (excessively many) e-mails at the start, you might not have ended up being what you say is rude to her. When this kicks up again, over something else -- and I would bet you there WILL be other dust-ups with her because she sounds like a classic drama queen out to get everyone's attention -- nip it in the bud much, much earlier: "I'm sorry you feel that way about (issue X). We see it differently. I'm going to drop the subject and hope you can do the same and we can continue to be cordial." And nothing else.

You are right; you cannot trust her any more. I've known folks like this -- with some good in them, but basically so used to getting their own way through throwing adult tantrums that they cannot be trusted to behave rationally. If she is asking to pick up your child again regularly, I'd just tell her "We've got an arrangement in place and changing it now would disrupt (child and pick-up-person's) schedule so much, so let's leave that." Any chance she gets to see the kids should be kept short -- have her see them and you at specific outings, with a time limit and a definite beginning and end, as opposed to "come over and hang out endlessly" situations. Then you always have the clock to blame when it's over. That approach can do a LOT to defuse her "need" to see the kids; put YOU in the right because you are indeed letting her see the kids and not keeping them away from her; and it gives you a great "out" of "Child needs to be at X in 15 minutes, so we have to leave right now, but we'll see you on Date at Time for Event." We have to do this one relative and it does work. As your kids get older and are busier, you will end up seeing less of her anyway.

I'm not sure how old you guys are or how long you were friends before this silly incident, but I think you both need to agree that somehow you let the train run away till it jumped the track. Apologize to each other, give each other a hug, and get past it.
I have lots and lots of friends and we don't all have the same value system, life isn't meant to be that way.
All of a sudden you cant trust her.... why?

I am not sure that I completely understand here. She did not agree with a parenting choice that you and your DH had made and repeatedly made an issue of it with you. Finally, you had had enough and responded back to her in a rude fashion. Consequently, she went off the deep end and demanded an apology from you both? Then, she refused to pick up your 4 year old from preschool anymore and that caused significant problems for you?

Before this, was she picking up your child as a favor and you were not paying her to do so? If so, even if it was spiteful on her part, it is within her rights to decide that she no longer wished to do that favor for you anymore. Nothing says that she is required to pick up your child...this is pretty much why depending on family for childcare can get so dicey.

Since it is his sister, your husband really needs to be the one to talk to her first. You've hit the nail on the head...you cannot count on her for kid-related stuff. If you really HAVE to have something done with your kids, don't ask her to do it. It sounds like you have an alternate pick up strategy in place...use it regardless if you mend stuff with her or not.

Make friends and be nice if you want to but do NOT leave yourself vulnerable to her whims/temper.
It's perfectly fine to have some boundaries - she doesn't have to like it.
Don't rely on on her for picking up your kids - she can visit in other ways.
Conflicts happen, but we can be grown ups about resolving those conflicts.
She over reacted and tried to hold you hostage, and you called her bluff and didn't cave in to her - good for you!
The kind of apology that's needed here is 'I'm sorry <you're such an idiot>" - it's up to you how much of that you actually say out loud.
You might care for her, but she's lost some of your respect.
I'm not sure she's interested in earning it back.
Sometimes you have to agree to disagree and not have a snarling dramatic blow up over it.
I'm not sure she can ever manage to do that.

I would sit down with her and talk. Apologize for the rude tone of your email, but make sure she understands that you still feel her emails and her response to yours were all out of line. If it is convenient I would stick to the new arrangement you have made regarding your child, you never know when she would decide to play that card again if you let her start picking him up again.

It seems as though she may be too ingrained in your family, and does not agree with your parenting. She needs boundries. I'd definitely keep your current child care situation at just about all costs.

She is using your children as leverage to punish you because you are not agreeing with her or because you made her mad. She can not be trusted or depended on.

Who knows what she is telling your kids behind your back, frankly, if she thinks you are doing things so wrong (in her opinion). Given what you have said, she is probably the type of person who will either directly contradict you or at least imply you are in the wrong, infront of the kids. This type of undermining behavior is bad news, for sure, and will hurt your family in the end.

My suggestion would be to talk it out with her (with your husband present), while the kids are not around. And no matter how Kumbayah you leave things, tell her you will keep your current child care situation, that you have so appreciated her help in the past, but would love if she wanted to take the kids to dinner/movie/park, whatever is a limited activity.

Ask your husband to deal with his sister. Ask him if he will be willing to have the major share of the communication with her from now on. He can tell her that you all have come up with a solution to the pre-school pickup situation. If she offers to help again, he can say, "No, thank you. We have another plan." When you all need help with things, don't get her involved. She can see your children when the whole family gets together for a holiday.

I despise family drama, too. But your post makes me wonder if we somehow have the same relatives! :^)