well...I'm like you too...trust issue and jealousy...and I think when you think this way, things are happening too...I found out, if I think positive and push those thoughts away, then good things will happen....
if you like her, just trust her and don't be afraid....what will happen at the end? if you don't trust her, it's possiblity of losing her....but if you trust her, then there is possiblity to stay with you....
you got to over come your fear...I think you protect yourself so much....I know it for fact....I'm so afraid to get hurt that I'm creating the situation and I'm the one who get hurt and stay alone!

take care and be relaxed....she likes you and he's the EX
Marjan