I need to rant, I have been so stressed out all weekend!!!! :O

So, about two weeks ago I put my foot down about caring for skids while FDH is at work. I have them for about 50% of the weekend when he's working (which is 50% of the weekends that we have them). I work full time and go to school full time and my school work is falling behind so I said we needed to work something new out, especially since BM2 keeps deciding to drop the kids off early, and I then have to get off work early. (when she doesn't work by the way). Also, SS5 is handicapped and needs constant attention which I can't give him if I'm trying to study, not to mention he's getting too heavy for me to carry, but that's a whole other thing. So this was brought up to BM1 and BM2 (yes, there are two of them!!!) and they immediately turned it around to 'she doesn't like the kids', :? which actually isn't true, I really like the skids, we have some problems with them listening and fighting but at their age it is totally normal.
So last weekend we had SD9 and we were at her swim lesson when BM1 took FDH aside and said they needed to talk, he said this isn't the time or place I don't want to talk to you right now. She freaked out and took SD9 home after instead of letting her go with us like she was supposed to saying that he wasn't allowed to see her anymore, he is done. Then this past weekend got mad because we had SD7 and SS5 and didn't take her child. Um, really? You said that he couldn't take her anymore!! And then she proceeded to tell him (again) that he would not be seeing SD9 until they go to mediation or court because she won't let him disappoint her anymore. HE isn't disappointing her, BM1 is by not allowing him to see her!
And then this weekend, FDH tried to work out a new schedule with BM2 on Friday when he was picking up kids, and she called me selfish and a b***h, and that I do nothing for the kids, nothing got resolved. Except me getting upset when DH came home and told me and I couldn't believe he didn't stick up for me. (I watch the kids 17 to 21 hours a weekend, I paid for SD7's gymnastics, I buy their clothes and toys, etc). Me needing to do well in school does not make me selfish, those kids are NOT my responsibility, I help as much as I can and I didn't say I would never help again, just that I couldn't as much.
So he went back last night and they had things pretty much worked out, and then she started bad mouthing me again and he said ok, the conversation is over if you don't stop. She didn't so he started to leave and she screamed at him to never come back and that he would never see his kids again.
I feel like this is all my fault!! I know it's not, I have every right to have my life and pursue the things that I was pursing (long) before I met FDH, I don't need to (and won't) wave the white flag and let them walk all over me like FDH usually does. I don't know how this all escalated so quickly!!