Pregnant & betrayed

My ex & I (still hard calling him ex) have been together 2.5 years. We got pregnant with our son accidentally right away. Today is my baby’s 2nd birthday. We got unexpectedly pregnant with twin girls a few months back. It all seemed so great. We fought at times but he swore he was a faithful guy. After my sons birthday this Saturday I was woken up to someone pounding on my door. It was my next door neighbor. He informed me that his wife & my guy had been having an affair for months. My guys response was that they were in love. My entire world fell apart with those words. He blames me & sure I wasnt perfect, but to do that.... Now I have found out about others. He has since bragged to me about all the hot sex they’ve had. I’m completely broken. Had to leave my job because of childcare issues, my days consist of trying to comfort my 2 year old because he doesn’t understand where Dada went, I’m unable to eat, have been smoking, completely unhealthy for my unborn children, but I can’t help it & all he does is blame me, throw his new love in my face. I have finally stopped communicating with him yet want to reach out pathetically hoping he’ll come home. My world is crushed. I don’t know how to get through this....