Rosey,
I really don't know all the details, nor do I need to know. I hear you you've been cut deep and often and for too long believed for the best out of the situation. Sounds like you got screwed but being female does not make that exclusively your problem. I could go on about my pain, been there I think I have a little perspective, being human and in involved different relationships all my life.
So go ahead my dear VENT get it out, don't let it eat you though your too good of a person to let someone who as you say lives for no one but himself, to continue to ruin your day/life.
It will take some time but trust me cause I am in your age group actually your senior when I say its okay to be angry, it is what you do with it that determines if this makes your a more wiser about whom you invest your time talent and love into the future. Trust me I have invested as well only to learn the same as you there was no return on it whatsoever. You're still young and you'll come out the better down the road you have too you've got no other choice so JUST DO IT, move forward don't get brought down by past hurts. If you do you'll become bitter and won't trust anyone again ever.
Oh so tomorrow when you get up first thing you do is toke and listen to my friend...
His words always pick me up....
Here's to a better day tomorrow for today is done!