I have become a single parent twice. First time was when my 3 elder kids’ dad died suddenly, and 2nd time was with an asshole who did these kind of things; cheating, lying etc but was also emotionally abusive. I managed to coparent with him for a while til he buggered off impregnated another woman and stop bothering with DS.
In my experience its so much less emotionally draining not having him around, and the child is much more content without conflict around. So if he kicks off or tries to fuck off then remember this, itll get you through.
Im not going to lie its not easy at times but dont do what i did at first which is bend over backwards for the bastard. Theyre often not worth it and its mentally taxing.
Coparenting needs you both to meet each other halfway but definately put boundaries in place. Ie; when n where to have contact and the latest he can call, paying towards expenses etc. My ex didnt like this but child support gave him no choice.
Theres plenty of resources out there, benefits, childrens centres with baby classes, local childcare, homestart, gingerbread and of course family. Most important of all, take good care of yourself and do things that make YOU feel good. Being a single parent doesnt mean you cant go to work/ do that course, exercise, see friends, go clothes shopping... it just means you adapt around your baby.
My opinion is that me and ds are happier and better off in all kinds of ways, without giving me sleepless nights worrying about trying to make an undeserving man satisfied.
If you decide to coparent, and you struggle to reach amicable agreements, you can get mediation to come up with something.
Im sorry youre going through this, men can be utter bastards at times 