You've posted about him before, haven't you? Asking you to go to mediation? (apologies if it is mistaken identity).
I think at this point you have to let go of the idea that he thinks the baby isn't his. Obviously it is a high conflict situation and for your own sake, and the baby's, you need to be minimising stressful thoughts and thinking calmly about a way forward.
It isn't possible for him to take you to court or start proceedings until after the baby is born. You need to make sure he has had a clear message that he is not to communicate with you (or family members) and that you will consider it harassment and take appropriate action if he continues.
If you know he will take you to court (and I don't think crushed is right, I don't think he has to have a DNA test to apply to court) it would be sensible to try to avoid that; telling him you will let him know when the baby is born, offering to put him on the certificate are both things that he can get anyway, but the offer may serve to diffuse some of the massive amounts of conflict. You can show the court you have been reasonable and mature and he will look more unreasonable.
I don't think you need to worry at all about your MH issues (in terms of having the baby taken away, obviously it must be a very difficult, anxious time and I'm sure it is having an impact) - you've managed the condition for years, you have family support. Don't get drawn in to the drama, keep yourself as distanced as you can from him and try to enjoy the rest of your pregnancy.