I need advice

So about 3 months ago I started dating my now boyfriend (he has a baby on the way and his baby mother is 3 or 4 months pregnant) he told me about this, but she got pregnant before we even were dating so I accepted it because he was honest about it and told me. We’ve introduced both of our kids together, spent so much time together, he takes me on dates, concerts he’s just really been a blessing in my life. But his baby mother has been absolute hell. She’s texted and called him non stop, talked about me, made threats towards me. She’s just mad because he doesn’t want her. She also told me he cheated on me with her in the beginning of our relationship which I believe to be true since she showed proof, but since then he’s built trust with me.

We came by her house to talk to her but he told her I was gonna fight her which wasn’t true. I also texted her and called her a stupid bitch after I was really upset she kept bashing him over social media. She said she was sleeping with other people so when she called him I answered his phone and I said “how do we know that’s his child? Give him a dna test then” she told me to mind my business but I told her this IS my business bc he’s my boyfriend. Ever since then she’s spiraled out of control.

Tonight she texted my boyfriend sending him photos from google maps from the front of my house and my moms house and somehow she knew my sisters name. She’s stalking me at this point. He’s put harassment report on her. She just won’t stop but I also don’t wanna leave him.

Can I please get some advice? I feel stuck and don’t know what to do. He’s a good man in a bad situation and it’s putting me in one too. We don’t even know if this child is his but I have 2 kids (not by him) and he has 3 kids w 3 moms and if this is his she’ll make 4 but I don’t want any judgement. Just advice.