Husband lives in another world

My husband doesn’t show any interest in our son. He (son) is 1.5 and yet he (dad) keeps saying that he will be closer to him when he will be older and do more things. I didn’t know you can cherry pick the moments of your kids’ life when you can feel like making a commitment??? My son and I have just been away for 10 days and he video called to see him just once! The other times he called me and I switched the call to video because I wanted my baby to see his daddy. And the saddest part is when my son saw him in the video he was so excited and happy he even started dancing! My heart breaks every time…he does the very bare minimum and obviously our son is now much more attached to me than his dad. So my husband takes it as an excuse and does even less effort to play or stay with him at all. Anything that regards my son is my responsibility, but I also have a full time job, you know?? The other day he was expecting me to thank him for bringing our son to the doc appointment as I couldn’t go because of an important meeting. My son stayed home for 2 days after that and guess who needed to take care of him while also working? Guess who didn’t call to check in on us?

Before you think I married into this knowingly, my husband has another son from prev relationship and he is totally different. He really goes out of his way to do things with his son and spend quality time and it has been like this since his son was 2- he is now 11.

Honestly I’m at my wits, I am considering to split up but I am eaten by the guiltless towards my son as well as the difficulty of letting our marriage go. We tried therapy but he doesn’t commit to it so we do 1 session every month/ month and half. How would you face this?