learning to trust

So from being in two terrible mental and physical abuse relationships, somehow i find the love of my life, but i cant seem to find enough trust not to worry about cheating. I've caught so many lies, im scared. this boy is so perfect. its hard to believe i have him, but with somebody like me? he tells me the only reason he was with his ex is because he didn't think anyone else wanted him. am i just another? or could he be being truthful?