He never stops.....

Recently I filed a PFA against my ex due to some abuse issues mostly verbal and some physcial. Primarily due to my sixteen year old's boyfriend that her Dad wanted her to break up with after they were together quite some time. His only vice was that he told her to stay away from her dad because she was afraid of him and her dad saw it on her cell phone in a text he had sent her. It got pretty bad for a while so I filed for and was granted the PFA.. Things have calmed down a bit but now he has my two youngest convinced that they should live with him because I still allow my 16 year old to see her boyfriend. She's an honor student plays on varsity b-ball and holds a part time job. she deserves to be happy after the hell he (dad) put her threw. anyway...if he takes the two youngest away...I know he'll reduce the amount of child support he currently gives me...which I use to pay my rent. He stopped paying the mtg on our home to force me out and I've been hoping from place to place since wtih all three kids in tow. Now I'm afraid that he'll reduce the amount of money he gives me and I'll be forced to live in a one bedroom apartment because I won't be able to afford much else. He makes about 60 thousand a year while I make 27 thousand. Is there a chance he can sue me for support if so I swear I'll go to a homeless shelter. I think my two youngest feel like he's the victim because when he was served the PFA he cried and they've never seen him cry so they're a little protective of him. He's also controlling kinda like Hitler.So I'm sure he's taking advantage and making it seem like I'm the bad person. A littel help please!!