I found out that my boyfriend lied to me?

[Crazydust407]

he has betrayed me way too many times and i know it seems irrational to be mad about something that happened a year and one month ago but he's done this before.
when we were dating at first,he told me that he broke up with his ex months before he met me(and i believed him)
then he later told me it was a week.
he kept in contact with her and also told me that he had plans to go to prom with her before he met me(but of course i wasn't comfortable with that,so he told me he would not go!)
and i believed that he didn't go and i was happy...i deleted my facebook a while ago ,but i just reactivated it and saw the photos of him with her at prom.the prom was a year ago. the way he's looking at her in the photos are inappropriate and it looks as if they were still dating.

keep in mind my boyfriend graduated already. she was in a year below him(attending the same school),so that is why there was a prom.
he was in college already and so am I.
i also caught him flirting with another girl,awhile ago in his facebook inbox(he accidentally left it open)
and went to his supposed "friends" house .everyone knows she's a hoe.
i just feel like he doesn't care about me,just him,it feels as if this is the last straw.i feel betrayed and walked all over.am i wrong for feeling this way ?

he said sorry ,and now his facebook,twitter and instagram are all gone
the photos from prom on his ex's page are gone too

what a loser
thankyou guys
i was trying to figure out if my feelings were irrational :/