Heya OP
First of all, I have a prerequisite for you; search 'Desiderata' on Google, and read it. A bit random, maybe, but it gives me perspective whenever I read it. You have to realise that.. Well.. There are bigger and better things in life to think about. Despite how you're feeling, there's always some good about the situation, even if it's tiny.
Anyway. I empathise completely. I don't think there's any magical cure for your state of mind at the mo other than embracing your fear and doing the impossible. Like everyone's said, learn to love your
self, trust your judgement and learn to trust. It's the only way you'll find contentment, methinks.
A while ago, I was at a stage like yours. I was nitpicky about texts from my then-boyfriend and most often felt excluded from his life because he was more of a quiet type, even though to me, in the grand scale of it all, he was the best thing since sliced bread. I loved him with every fibre of my being. But then there was always unrest in my mind, and I let things bug me- I think at one point I, too, got kind of fixated with his ex, even though he'd expressed an obvious dislike for the girl, and to be honest, I think I was going through the motions of being a difficult girlfriend because I didn't know what to do with myself. I bit the bullet and decided to go with my overreactive emotional mindsplurge and eventually ended up kind of unintentionally telling him to change. Something like, I don't feel like I'm properly involved in your life, you need to be more open, or I can't go on. I imagine he took that quite hard, and was insulted by my behaviour- in retrospect, I know and
did know that there should never be any need to ask someone to change who they are, and to this day I think that isn't really what I wanted. I was in a crazy place.
So.
Reasons and arguments aside, my problem, I've come to believe, was that I didn't know enough about myself, what I valued and what I could deal with before getting into this awesome relationship.
I'd brought with me my insecurities from the past, and my preconceptions from other people's relationships, possibly resulting in one of the most painful mistakes of my life thus far; I lost the guy I loved. What can I do but urge you to detach yourself from the situation and think about what /matters/- this guy /loves/ you, that's evident, and probably has no clue how to fix what you're going through, because it's all self-inflicted, even though he'll want to make it all go away for you. Put yourself in his shoes, and learn to see what he sees in you. Some insanely amazing, vastly good-looking, all around beautiful girl that he feels lucky to be with, probably. Learning to respect who you are and appreciate your faults and strengths is not the same as being arrogant, vain or self-absorbed- it's a necessity for you to be able to put your heart into a relationship and make it work, otherwise you'll have no strength left for yourself.
Anyhoo. That's my two cents. I really hope you find it in you to take a leap