Severe stress and pregnancy

I am currently 20 weeks pregnant. I had been with the father of my baby for 8 years in a long term relationship. He asked me to get pregnant, and was happy initially with the pregnancy. At 11 weeks, I had my first ultrasound which he was allowed to attend. After that, he started treating me like crap. He won’t speak to me, hasn’t been to my house in 10 weeks. He doesn’t text or call anymore. He’s always on his phone but never with me. He and I had such a close bond before this baby. He called and texted constantly no matter what. He was very affectionate and loving. He always held me, was touching me. We had an active sex life. He was always happy and excited to see me. He’d miss me as soon as I went home. I thought we would have moved in together by now and he’d want to get married. Instead he’s nothing but cold to me. He’s cut me out of his life with zero warning. I suffer from borderline personality disorder, panic disorder, anxiety disorder, and bipolar 2. He said nothing about our anniversary in November and we didn’t celebrate thanksgiving together like we have for 8 years. I am so sad and heart broken. I can’t understand. He has just thrown me away. I am now dealing with severe anxiety, depression, and stress. I was gaining weight well with my pregnancy after always being significant underweight but now I haven’t been able to eat and am going days with no meals. I don’t know how to handle this level of pain and what to do anymore. I’m afraid I’m going to lose the baby from this.