In need of support and advice

My partner and I planned baby #2 and had the most wonderful family holiday in May which is what we needed as we had been having a few patches but after 6 1/2 years together we always came out the other end, August bank holiday he went out and didn't come home until very late so I locked the door and told him to go to his parents he said if I did that he wouldn't come back - I'm pregnant we have a 4 year old I took it as an empty threat- fast forward 11 weeks and I'm still single he's actually seeing someone and started  to date them a week after he left me - I do know this is the true thing since we finished I am 21 weeks pregnant and very hurt very sad and I miss him dearly, how can he not miss me? How can he move on so fast? This woman is 30 years older has no kids and he thinks she's Jesus and I'm the devil, I am nothing but a chore to him and I'm now having more bad days than good, I feel like my whole life is on hold wondering will he ever be sorry. We had life plans together how can he turn his back on his family - I'm a broken person and I feel like I have no where to turn. His family were my family we were so close but the constant arguing between me and my SO is taking it's toll on everyone and I feel like I should cut ties unless it's for the grand children 😢😢😢😢😢