Whats wrong with my Boyfriend? is he hiding something? am i over reacting?

we have been together for 2 years.he used to live in DOM. REP but he now lives in NJ and i live in MA. our relationship has been long distance. i am afraid he changes since U.S is a new country for him. he still tells me he loves me, kisses me in the forehead and hugs me. but when he was in my house over this christmas he was on the computer and i found out he has a hidden messenger and a hidden myspace he dont want me to know about because he was hiding it..i am really jelous. my sister told me he was talking to a couple of girls through the messenger. he wasnt like this before. i recently been love sick with him.i am afraid he dont love me anymore. i cry alot, i think about him alot and i dont want to seperate from him. i am afraid of getting hurt. he left this morning to NJ and told me he missed me and loved me but i dont know if i believe what he says because he was lying to me yesterday...HELP Me please..this is totally killing me.. i feel like dying right now...i also dont know if i am over reacting..what can i do so he can catch strong feelings for me again?