It sounds like there are so many different things happening in your family right now. I understand you feeling you could use more help, but it sounds like your mom couldn't possibly take on another responsibility. That doesn't have to mean that she loves you any less or doesn't care about you.
It sounds like you plan on leaving your husband at the end of the school year. The school year just started, so you have some time to figure things out. If you are considering moving, I would look into areas that have morning programs for kids or a daycare that will provide transportation to school for your children. Maybe you don't even have to move. Find a mom that already takes her kids to school in the mornings and see if you can pay her a few bucks a week to take your kids or offer to watch hers so she and her hubby can go places. As a single mom, I've traded lots of things like that go get help.
You can't start thinking that you are doomed because of something someone else can't or won't do. You just can't think that way. Ultimately, your success depends on you, and you CAN make things work.
Listen, my mom loves me, but she doesn't help me. I just moved out of a house that I'd lived in for 8 years. She never once made the drive to come see us. Now that I've moved, she doesn't even know where we live. She'll call me in October wanting to know where to send a Halloween card for my son, but other than that, she doesn't worry herself about me. I know better than to ask her for help. She raised me to be independent, I'm 47 years old and that's too old to be asking mom for help, in her opinion. I took her in and supported her and even got her a job in my office when she went through her divorce, but I guess that was different.
Get counseling so you can get yourself centered. Realize that whether you make it or not isn't dependent on what someone else does. If one thing doesn't work out, always have a Plan B. Or Plan C. Realize that you have options, you just have to get creative in finding them.
If people don't adjust their lives to fit what works for you, look in a different direction. It doesn't mean defeat.
I always thought it would be nice to have a big supportive family, but I don't have that. So....I have come to realize that even when I have to struggle with things, there is really a satisfaction that comes with knowing I've been able to manage for myself. I have built a network of neighbors and friends and co-workers who I can count on in a pinch and they know they can count on me.
You have a lot going for you. You have to believe that.
There's always more than one way to get something accomplished.
I wish you the best.