It just shows you're part of the human race! I bet you'll get all sorts of answers, and I hope it will help to know that even though you feel all alone, just about every other mom is going through this - or has - or will!
Consider your eleven-year-old a teenager; kids begin all that crazy teenage stuff earlier these days. That means you'll need all the focus, all the wisdom, all the strength, and all the humor you can get.
I know exactly what you mean about making your family's lives happy. But when you get down to it, only they can make themselves happy, and only you can make yourself happy.
You supply a lot of other stuff they need, though. Just don't expect a lot of gratitude. That's not the way people are wired. When you were a kid, did you thank your mom for what she did for you? Me, neither. We probably didn't notice most of it - we were centered on ourselves. I read in the Bible that of ten sick men Christ healed, only one came back to say thank you.
Try to figure out some little changes you can make in your daily routine for your own benefit. Take a look first at the amount of sleep you get at night, what and when you're eating, and what you're doing for exercise. Your "coach" can undoubtedly help you make little, inexpensive, time-friendly changes in these areas. It may seem contradictory to work on yourself when you have a family to take care of and course requirements to meet, but you can do your work better when your body is healthier.
It's not selfishness; it's just common sense. You know what your husband, your children, your pets, your car, your house plants, and your furnace need to be healthy. If you're going to do your many jobs you need to be healthy, too.
As you go through your day, look for anything, and I mean anything, that's a day-brightener. Little things can be a lift: a smile from a clerk at the grocery store, a kind word from a neighbor, a positive comment on a paper you write for a course, a flower blooming in an odd place, a song you enjoy, moments when your kids are really, really nice. Look for anything you can laugh about, too - even if it's laughing about yourself. Sounds corny, but looking for the good things and savoring them can actually help you do your important wife/mom/student work.
Be selective in what you choose to have going on around you. Try (gasp) turning off the television and see what effect it has. Try different kinds of music on the radio instead and see what effect that has. Play around with the options, and see what lifts you up best. Or write in into your schedule to sit down with a good book (not a textbook) for five minutes a day. If you can't sit down with a good book without finishing the whole thing, forget I suggested it.
Be very selective about whom you tell your troubles to (this forum seems like a good place) and whose troubles you listen to. Don't allow whiny people to drag you down and focus you on what's depressing.
All this may sound stupid and Pollyanna-ish (by the way, "Pollyanna" is a much better book than you might think), but it can help you get yourself standing tall again. You are an important person with important jobs and VIPs to take care of. Take time and energy to make yourself healthy in body and mind, and your VIPs will benefit, too. Don't even tell them what you're doing; make it your own secret.