D..
I'm sorry, but I just wanted to crawl in a ball, figuratively, when I got to the part where you said you still loved him and wanted your family to be back together. What on earth are you thinking?
Of course your husband has bipolar disorder. Of course he was having sex with this woman. Of course he doesn't want to pay child support and wants the money from your daughter's disability check.
Straighten yourself up. STOP having sex with this awful man. WHY do you think SO poorly of yourself that you would put up with ANY of this from him and take him back into your bed?
I would not have another child in your circumstances. But that is me. You will have to decide what to do if you are actually pregnant. I hope very much that you aren't. I think that you WILL lose custody of your kids if you are pregnant, as you won't be able to take care of your children OR work to provide for them, knowing the complications you have. That's what he will tell the judge. Lots of mothers who don't work outside of the home find out this hard truth nowadays.
You need to have a lawyer's help here. You need to stick with the facts of how he acts since you will never get a diagnosis of bipolar disorder that he won't get from a doctor. Ask the lawyer if you can get a letter from the guy at work to give to the judge. You want as much real documentation of his impossible behavior in order to show the judge that he is not stable. In fact, perhaps you can get the judge to only allow the children to be with him when his parents are with him. I certainly wouldn't want to trust him to give his daughter her diabetic meds or check her blood sugar levels. THIS is what you want the judge to be thinking.
You two met young and married young. He has decided that he doesn't want children and a family. He wants freedom. He is not mentally healthy either, losing his job over getting into a fight with a coworker. Things aren't going to get any better.
Please wise up and stop being with this man at all. You are fooling yourself if you think that he will ever be the man you want him to be. If you screw this up, he's going to get custody, make you pay him, and dump the kids with his parents. I can guarantee you that he won't be giving his parents the money to take care of those kids.