15.5 years together and 8 months pregnant to realize he’s not in love with me anymore

Well this is a long story that I have kept to myself expect for telling my best friend. I feel like I need to talk about it but don’t feel like talking about it to people I know, I’ll try and make it as short as possible, back in December I was 8 months pregnant with our second baby, we’ve been together for almost 16 years and already have a child together, both kids were planned. I thought we’ve had the best couple of years and really was wrong. The last year and a half we have been more intimate then ever and I thought everything was great. At the end of October his dad got sick and he took off to be with him, eventually his dad was waiting to get surgery and while his dad was in the hospital waiting for surgery he was staying with a female “cousin” they are second or third cousins, and have always been fairly close. He was away for almost 6 weeks and the whole time I just had the feeling he was distant and would get really jealous when they were out doing fun things and going for supper all the time while I was home with our child and pregnant and working 40hrs a week. Finally when he came back home things didn’t seem too weird other then he was constantly on his phone texting with this “cousin” one night he got really drunk at our place alone and I woke up and could hear him talking so I went to the stairs to listen and heard him talking to his cousin and saying he loves her and she doesn’t know what he’s going through and blah blah blah, I went down and asked him what the call was about and he broke down saying he doesn’t know if he loves me anymore and that his life is so fucked up... we talked about it the next day and he said he just can confide in her and they got close while staying there and that she is just support for him, he said he wasn’t leaving us and he would go to counseling to try and figure his shit out, within the next few weeks he went back to visit her a couple times for the weekend. Fast forward a baby and a few months later we don’t kiss or say I love you anymore we went to visit her again and one night turned into a full weekend. A couple weekends later he got drunk again and I heard him downstairs talking to her saying how much he loves her and wishes he was there with her, that night I went through his phone to see what they actually talk about and of course he’s having a full blown “emotional” affair with her. He would text her every morning “good morning beautiful” and they’d text all day how they wish they could be together and send each other songs that remind them off each other. I’m broken, I’m mad, I’m sad, I’m tired, I’m lost. It’s one thing to not be in love with me anymore, you can’t help the way you feel but its another thing when it’s influenced by someone else. Especially someone who has been around during our entire relationship. If he gave our relationship half as much attention as he gives her we wouldn’t be in this spot. I hate going to bed together with a friendly goodbye, I hate that I have to put on a brave face daily for my kids, and my family. The worst part is loving someone so much and giving them your all and getting nothing back. I love him and for some reason still feel like we need to be together but I know I deserve more. I don’t know how we sit in this floating state and when or if he decides he wants to be with me how do we build a relationship up from nothing. I doubt anyone’s continued to read this far but it just feel ma good to get it out.