What do i do?!?! ....

Sarah

So my husband and I split up back in May of 2015. In August of 2015 he slept with someone and got her pregnant .. She is due in 25 days. In the beginning he told me he didn't want anything to do with the baby cause she got pregnant on purpose after telling her he didn't want a kid. She lied about using spermicide and poked holes in the condoms. Well while him and I weren't together he was pissed at me for leaving so be made up lies about me. Apparently making me out to be a bad mom to the point she is in fear of her son's safety if she was to allow him to come here. So she told him that as long as him and I are together than he will be financially involved in the childs life but it will go no further than that. So my question is .... Do I stay and we battle in court for the rest of our lives or do I leave so he can have all of his children in his life without the hassle. We have two kids together and I am 19 weeks pregnant with our third... Sorry, I forgot to mention we got back together November of 2015.

I'm looking for advice so please no rude comments.