Fake it to Make it

I'm not legally divorced because my ex and I never legally married. but by the state of Texas we are considered as such. I broke up with him about 2-3 years ago. he was constantly accusing me of cheating and suspecting me, so I broke up with him. we have two kids and still live together. but only because I have nowhere else to go. the past few months recently (currently) I've been attempting to play the role of a renewed gf and it is very difficult. I don't like doing things I don't want to do it like doing. if he has any reason to still suspect me of sleeping around on him it's because I have (1 partner) 3 months after I broke up with him and I have had that one partner ever since. he thinks I have multiple but I tend to let him have his rant about that because hey, why would he believe that or why would he need to? I don't know what I'm asking for exactly; answers, advice, anybody who related idk. I just know that as of right now I'm the only person I know who's going through my particular situation. I'm faking it to make it. I need my own car and co parenting is the only way to get there so I can leave securely. we keep fighting when he gets drunk and the last time was the worst of them all. Help. Advice. Ventilation. anything will do.