I have been in two relationships in my life (I use the term loosely for the first one).
I was 19 years old, had incredibly low self esteem, hated myself, mostly, so, at my job, a guy liked me, and, long story short, I wasted 10 years of my life with that fool because of my insecurities and being afraid to move out and be on my own, as I had gone from living at home to moving in with that douchebag, so, yeah, the fear of being in the world on my own scared the hell out of me, and I refused to go live at home, because I was an adult who wanted to learn how to deal with adult situations instead of running back home. I wanted to make it without help, as I was never, and still am not, the type of person who likes to ask, or rely, on help. I was treated like garbage, made to feel worthless, I can honestly say that, if it were not for my pets (I still have them), I most likely would not be on this planet right now. I was made to feel that I was not good enough for anyone.
In 2014, my friend told me about the place next to her being available (apartment). I finally said eff this loser and split. I thank her for that push, and I am still in this apartment, neighbour to my friend, and with a great fiancé, who treats me like a human being. I could not be happier.
Relationships will be garbage at times, but, don't let past ones mess up your future ones. You could be missing out on a great life if you keep fearing pain. I had no pain when I left, but, if my fiancé ever left me, I would be a wreck. Still, you can't let pain keep you away from possible happiness. If you have to go through pain, you know what it feels like, but, you also know it will pass.