what the hell? Options

[*Weird addiction*]

Is this guy hitting on me?

last year, my friend gave my msn address to her boyfriend and he added me. Never seen this guy, but we chatted alot. First he sent me porn pics, really disturbed me. I didn't say anything to my friend. Then he started having problems with his gf, he told me he had feelings for someone and he was thinking of leaving (ange) but i advised him not to and bleh... then he said he was going to come to my school just to see me, i thought he was joking but last friday, he came , ange introduced him to me, and he kept on smiling and winking. Today, on msn, he changed his display name to *my girlfriend loves me but i can't stop thinking of you*. I noticed that he doesn't really like leaving or when i'm leaving. This happened 2 weeks ago:

me: i have to go
me:ttyl
sam: no, stay, pls don't go
sam: kidding bye
me: bye
sam: don't leave me, i'm not kidding, please wait...sandra...please
me: why
sam: god, nothing, sorry, god...bye
he signed off

I had to save that convo

Even now, he said he was leaving, i said ok, he sent me kissing lips, then throbing heart. He said bye, i said bye, the he said "really want to get rid of me" and i'm like "no". He signed off, then came online and sent me a throbing heart and said bye, then signed off.

Is he hitting on me or anything? i don't understand him....if he is, shd i tell his gf?