Sexually frustrated in relationship

Have been with my boyfriend for close to 4 years now. We have a 1.5 year old together. Since I found I was pregnant, our sex life has been a huge issue for me. Not only do we have sex less frequent ( life happens, I understand that’s bound to happen) but quality of it is poor as well. I have easily spent the last year voicing my frustration to my boyfriend. Nothing comes of it. I communicate things I would like, nothing comes of it. We considered counseling for it, he said he would get it taken care of. Nothing came of that either. I’ve tried to have conversations about it, usually just turns into a fight. My frustration is at an all time high! I fantasize about having an affair because I’m so bored and don’t feel wanted or desired by him. He is unwilling to do anything I ask for sexually. He shows little to no interest in me or my body.

I’m at a complete loss here. Any advice?