Glad to hear it went well with your Mom. Sorry Step-Dad wouldn't stay to listen. I second what Jo said on the fact that once he sees what you are doing, maybe he will come around. If he continues to berate you, you can bring out the list again and say, hey I made a plan that I am sticking to. There is no reason for you to get on my case. Obviously you are unhappy with your life but that is no reason to take it out on me. You knew coming into this marriage that there were children involved.
I would check into finding out if there is a local community clinic where you can get your medications at a lower fee. They ususally work on a sliding scale. Car insurance - you might considered getting the lowest level (I think it is 15,000/30,000 coverage and up your deductible for now (unless it is already high. Consider a deductible of $500 or $750). Also, you might consider checking into any governement subsidized program for your jobs at the multiple school districts. Maybe they have some sort of program.
Good luck. Hugs and purrs.