If the guy I was dating willing signed the birth certificate and I put him on child support because he hasn’t done anything to help out. What can hap

I was dating this guy for over seven years and he was cheating back and forth. I begin to see another guy after asking him to stop and knowing that he had made a child with another woman. However, in between all of this. I ended up pregnant and I tell my boyfriend at the time that I wanted to abort the child because I wasn’t for sure if it was his or the guy I cheated with. However my boyfriend said “No” he didn’t want me to do it because the child could be his child and if it wasn’t his child. It would still be his child cause he would take care of it. The day my child was born my boyfriend signed the birth certificate without hesitation. He hasn’t done any for my child since. Now that my child is almost seven I decided enough is enough and I put him on child support. He now wants to take me to court and he secretly took a blood test for my child which turned out not to be his child. What can I expect at this point? Also should I get a lawyer as well?