Insecurities about his ex-girlfriend
I met my partner about a year ago but called things off as I had just come out of another relationship and needed time for myself. However, we remained close friends and there was always something between us. We got together officially 6 months ago but i found out (through snooping, more being nosy than insecure i think) that he slept with his ex at christmas, just before we got back together. I was devastated, despite the fact we were not together then, as this behaviour is completely out of character (he is so honest and has strong morals) and his ex was his first love. I feel i have to compete with her - she is physically much more attractive than me. I can't stop thinking about her and although he assures me he loves me i can't help thinking he could rather be with her. I know this is negative behaviour and i need to stop but i have no idea how.
To make things worse my partner and i will be living in different towns for the foreseeable future and i am already really worried what is going to happen. I don't want to lose him and he said he would be devastated if things went wrong but i can't stop feeling so insecure and thinking that the worst is going to happen. I trust him completely but my negativity and fear of being hurt makes him think i don't. I really need to build more confidence in my relationship but particularly in myself otherwise i am going to ruin a good relationship. Any advice would be gratefully received. Thank you.