How would you feel?

So I’ve been having issues with my bf and a girl he dated before we got back together and pregnant with our daughter. Now I’m pregnant with our second child and she’s been a constant issue since I’ve announced my pregnancy. They’ve been caught hanging out, I have no access to his phone, she posts things about him without addressing him directly, she tried posting about me saying this baby wasn’t his, threatening me in my messages, etc. Well recently, he had blocked me on instagram and started following her. I addressed it and he unblocked and unfollowed her. But now, he follows her again and all of her friends but he WILL NOT follow me. I said something about him not following me and he said he deleted his instagram but he’s been continually following more and more people on there. How would you feel about it and how would you address the situation?