Hello.
This sounds like many troubled relationships I've witnessed. Before I go on, I want to say that I understand the struggle. I also would like to preface this with saying that the choices are entirely yours, and sometimes that's the hardest part.
It sounds like he's having trouble figuring out for himself just what he wants/needs in his life. You are both very young yet, and there are so many options available to both of you, other people included. Perhaps he's having difficulty fulfilling a void in his life and utilizes other people (girls & friends) to try and accommodate for whatever he feels is lacking. This could be something he's completely unaware of, too, and is why he cheats--not to necessarily hurt you, but to fix whatever hurt he feels.
Next, to touch on your hurt, only you know what you feel. Your feelings are always true. By that, I mean that they are strictly because of something that is happening/has happened to you, and that is not wrong. No one's feelings are ever wrong. They can be misplaced or misquided, but not wrong. If his friends have hurt you in some way and you feel that, then you need to do what's right for you to make the situation better. If you need him to not talk to his friends for you to feel better, then so be it. That does not make you nasty or mean. That's you standing up for yourself, and you never need to be sorry about it. If he is unwilling to help you in that battle of standing up for yourself, you have a choice to make as to whether that's something you can tolerate. If you sincerely feel hurt by his decision to be with the friends that disrespected you, you need to decide if you can brush that off. From your post, it doesn't sound like something you can just let go of, hence your reason for posting.
Lastly, remember that everything that happens in your relationship now sets the foundation for your relationship in the future. If you decide to get over this now and have a relationship with him, you cannot hold onto this instance. You have to let it go. If you don't think you can do that, and think this might come up again, it would be better to walk away now. You don't want to be a year, 3 years, 5 years into the relationship and have this particular situation come up again, only to fight about it and blame each other and so on. That's not good for anyone involved.
I wish you the best.