Once a liar, always.......?

I found out through a third party that the person I am with started our whole "getting to know each other process" off with a string of lies. Apparently he also called me a psychopath and "just some annoying weirdo from POF." He has since come clean and we are together but I don't trust him for the most part. I keep saying it will take time but it is a bad feeling to be mistrusting of the person you are with, and honestly, even though we get along, deep down I am pretty hurt not only because of all the lies, but because of him there was a lot of unnecessary drama with his annoying ex-girlfriend or friend with benefits or whatever she REALLY was. I would also like to know why he keeps insisting he hasn't felt anything for his wife for a long time (he says its been over for 3+ years) when I found emails in which he tells her he still loves her about a year ago. Black on white doesn't lie. He supposedly didn't even write those emails...well funny, they are from his SENT box to HER email address...so please. When I try to talk to him about these things, he either just looks away or gets sarcastic/loud...and those signs indicate to me that he is STILL lying about things. What do you think?