Unattracted to my partner

I’m really just wanting some advice. My partner and I have a beautiful 1 year old son and am I currently 12 weeks pregnant with baby no.2. I had a very traumatic birth with baby no.1. He arrived at 30 weeks with an abnormal condition that took us all by surprise. It was tough but we got through it. About 2/3 weeks after having him, I started to really resent my partner. (I blamed his lack of help around the house the reason for preterm labour. I did not stop doing everything) he began to become lazier and lazier, he piled on the pounds and his whole attitude became really unattractive. We have our good periods and bad periods but he seems to have this constant bee in his bonnet. We rarely have sex, I think we’ve had sex 3 times since finding out I was pregnant. He is always on his phone, he looks at women on Instagram all the time. His phone goes everywhere with him. He doesn’t touch me, look at me, compliment me. Nothing. We are just two people raising a child. I find it so sad, we were so in love. I’m not attracted to him anymore, I haven’t been for months. We are having this baby in March and I fear that things will only get worse. I’ve tried talking to him but everything is my fault as per. I’m just slowly giving up & wanting to become a single mother. I don’t know what to do