Hi, G. --
It sounds like you're really in a difficult predicament. I need to first say that I do not believe being gay is "wrong." So, you'll have to take my response with that in mind. I believe being gay is generally genetically based, and there is, from what I've read, a relatively fixed percentage of the population worldwide who are gay.
In any case, your son may not actually be gay - but he may be feeling so low about himself that he is wishing to live vicariously through other guys who look or act or experience life the way he wishes he could as he tries to imagine what life would be like if only he were like them.
If I were in your shoes, I would absolutely NOT express any condemnation about his feelings that he might be gay. Rather, I would say, "Honey, you may actually not know your true orientation because right now you're clearly feeling unhappy in your own skin." I would address his own feelings of self-esteem and isolation IMMEDIATELY! The gay issue is, at the moment, far less consequential than what he's feeling about himself, since that is going to impact every single element of his life now and in the future.
Don't jump the gun yet in looking ahead to the possibility that your son is gay. In my view, if he's gay, he's gay - that will not be something you will be able to change and it will certainly not be something you will want him to hide from you. If you love him, you love the person he is, and you will want the most fulfilling and blessed life for that person, including for him to be deeply loved and cherished. If that love ends up being found in someone who's not a woman, however painful that sounds now, I hope you'd eventually be able to be thankful that someone loved him the way you do.
Anyway, I know you may find these statements really disheartening and disturbing, and I completely don't want to leave you feeling that way. I have a number of gay friends, one of whom I really worried about and hurt for because she spent so much of her life alone, "in the closet," taking care of everyone else but herself. When she finally came out and told us she was gay, and that she had someone in her life who loved her, I was thankful and relieved.
Anyway, your son needs some experiences right now that will build his self-esteem and his feelings of comfortability in himself. He may need some training in how to set some goals and achieve them to grow in him a sense of confidence and self-determination.
I'd say, right now, you need to get rid of the computer. That would be step #1 in my house. #2 - no more texting. He needs to get into the real world, with real people who he can interact with. This virtual world stuff is like poison for some personality types, and will only further isolate him. #3, if he's making bad internet choices right now and infecting his mind with perverse imagery, then he needs to be given opportunities to find other types of stimuli and interaction that will enhance his life and not tear it down.
I FEEL for your son in every possible way. It's SO hard for some kids, and that will mean that it's doubly-hard for their loving parents. He needs you to be a leader for him right now, to point the way to new experiences that will help him build up his inner man, and maybe his outer man, too, to learn his options for becomming the man he would like to be. He will be no less of a man if it turns out he's gay. I hope you can believe that.
Apparently, it's pretty commmon for kids to be sexually curious at this age, but with your son's tendency to isolation, I think he's got to be prodded to really get into the world and away from the shaddows.
I wish you only the best, and I hope some people here have some specific suggestions for you about these things.
Take care,
H.