Originally Posted by Spock
There is the possibility that her husband knew there was something screwy going on and she ignored him, too.
A number of people have said it - this situation was dipped in red flags from the start. The fact that it has spiraled into this bizarre Mexican Stand-Off shouldn't come as a big shock to anyone involved.
As far as paternity and staying with this guy, separate those two topics out entirely.
- Paternity: if he wants to have a test done then that is governed by the laws of your area. If it turns out the child is biologically his then he can assert whatever rights he wants to and that the law will allow. This is 100% beyond your control so you might as well just let it go.
- Dating Him: this guy is very clearly an unhealthy fellow. I am not personally on the "abuse" bandwagon but it should be painfully evident at this point that he is not going to be an emotionally intelligent partner and should be scraped off of you IMMEDIATELY. But, that is 100% your call.
OP, I hope that you take this as a learning opportunity.