closet gay problem

Hey guys, I am just a new member here. I just want to share my problem with you..

I am a college student, and was a typical normal guy. I have friends (who do not have any idea that i am a Gay/Bi) and a girlfriend. Things were pretty natural as it goes, until I met this guy last New Year at our dowtown.
He was a separated husband, with 2 year old son, but his child were on his mother. Meaning, this guy lives alone. We shared a seat in one of the fast foods out here and begun a small talk. Out there, we confessed to each other are closed sexual orientation, that we are both bisexuals. When he knew that I was a bisexual too, he immediately invited me on his pad, you know, to do the stuff. I was reluctant at first, because I do not have any same sex experience for my 18 years of existence.. but eventually accept because he was a really good looking man.
So I go with him and as the night falls, we started having sex. He was more professional than I am, so I let him do the positions. He was the top one, and I was the bottom. I was kinda freaked out at first becoz I was not used to be drilled, I am the one who usually drill my partner, but he said the next time we had sex, he will let me to go on top.
And so we had sex for 3 rounds that night, 1 hr interval after each one. I slept at his pad of course.

After that incident, it was never gone out of my mind. Fuck to say, but I miss him doing the stuff with me.. the worse part is that I like being the bottom one. It affected my relationship with my girlfriend, my interest on having sex with her decreases and my attention now focus on mr. New Years day. I tried to find him, one way or another, thru fb or twitter to learn his whereabouts ( I never got his cell number). Then on first week of february, we meet again. I message him on his fb and said I miss him so much, and he replied he's now busy becoz he's taking care of his son. But he said he'll gonna meet me if I will accept to have sex on him again. Actually I am not thinking about that becoz what I only wanted is to see him again, maybe I was falling inlove ( or crush) with him. And sex now is not important.. but I also said yes to his offer eventually..

after that, we saw each other again atleast twice a week, (we were long distance, almost hundred of kilometers away from each other) and everytime we see each other, he is insisting for sex.
I think now that i am really inlove with this guy, and its hard for me to decline his offer becoz If i do so, he will not come to see me. I want to see him very often, as much as everyday, becoz whenever we parted, I miss him instantly. but I am confused if he also love me or not.
when we were having sex, I always felt there is a passion.. he was very gentle and even kissed me on my lips, however, when we were casual, talking normally, its like we were nothing but an ordinary friends..

now what do I gonna do?
do i need to tell him about my feelings? do I need to leave my girlfriend? what if he also love me? is it better for us to become couple or what?
and the main problem here, I cannot say all of this issue to my family.. they do not know I am a gay or having sex with a man.. I know this will break their hearts if they become aware of this..

Aarrghh!!
and I love that guy so much, but I also love my family! and my girlfriend, wtf! I know I cannot leave her that easily.. I dont want to see her in pain

need your advice..