When I was younger, I had a string of crappy "relationships". My 1st "boyfriend" hid me from his friends and parents. Looking back, I see I was little more than his other woman. I didn't see it at the time because I was very young (17-20) and very naive.
After that, I spent probably 3 years going from one bloke to another, me hoping for a proper relationship but them only wanting sex and nothing else.
I got fed up with being treated like shite and feeling used and worthless so I was single for years. I didn't even try to meet another man for a long time because, like you, I felt as though all relationships were going to pan out in that way and that I'd rather be single than stuck in a miserable relationship.
It wasn't until I'd lived on my own for several years with a full-time job, enjoying living my life spending the money I'd earned that I felt confident enough to test the dating waters again, knowing that I could be happy on my own and that I didn't need to be with a man and that I didn't have to put up with crap.
I met my now dh at 28 and yes, we have a good, happy, healthy relationship. We work well together, we talk, we support each other, we love each other. We could do with more money and we should spend more quality time together without the dc but overall, we're happy.
I would advise you to not bother with your ex, only speak to your child's father about your child and spend time by and on yourself, working on your confidence and your boundaries. I believe that you should be in a relationship because you want to be and because it makes you happy and if it doesn't, you shouldn't feel stuck with it.
Yes, it does get better than what you're describing but only if you don't waste time with liars and cheats.