Hello, it is understandable that you are concerned.
If you are positive he is chatting to gay boys and men it's very important that there are some changes in the home.
First off I hope your computer is in a public part of the home not in his bedroom.
It's really important that you absolutely know who he is talking to. That is your job as a parent.
Since you've mentioned men and you know there are predators online looking for boys your sons age you will need to be bold about knowing this.
Whether a 13 yr old is gay or not doesn't matter as much as it matters that you know who he is talking to and that he is not accessing x-rated sites (you can get a filter for preventing this). You also need to know where he goes and with whom.
As with any relationship a 13 yr old son may have there are rules and they must be followed. And you are the one to make them. Later he will thank you for it.
At 13 he's at the beginning of learning who he is. Some teens right now think it's cool to say they are gay,lesbian or "bi"..but in truth there's a small sector of kids who are doing this. Perhaps your son thinks it's a way to keep people interested in him.
Maybe it's time to spend more time with him taking walks,talking,playing games,etc.
If there are two parents in the home you need to talk and get in tune with this child so he's not so bored that he's online getting gay men interested in him.
That's scary.And could be dangerous.
It would help if you had a counselor for him to see so do look into that whether he wants to or not.You are the parent.He is the child. You can help him by getting him professional counseling to enlighten him as to who he really is.
Hope this helps.Please click accept and leave a positive feedback as I will for you also.