you havent 'got' anything sweetheart. you seem to have severe self esteem issues.
make an appointment with your gp and ask about counselling services in your area. please.
i dont know why you feel this way, but i can sympathise, as i have felt the same way in past relationships, and if im honest, a little bit too, even now, but i try to keep it under control. it doesnt help that im now with a man nine years my junior, who is very good looking.
i struggle with myself, but i know he would never be unfaithful. its just my mixed up head.
i just think with you, these feeling have taken over and you feel totally out of control. you need constant reassurance, but your partner could never give you enough, no matter how hard he tried.
just try to explain that you do trust him really (as im sure you do) and that you just have some stuff in your head that you need to sort out. but if you are to feel better, i really would give counselling a go, as its sometimes impossible to do it all yourself.
all the best to you, really, and a big hug (((((((((((((((())))))))))))))))