I need advice mostly from guys

If he's a year younger than you, then he's only about 18. That means he is still going to be quite immature, and there is very little that you can expect from him, and you could be disappointed with his behavior.
Even though you might like him, it just isn't worth it.

If trust in men is the problem then this is something that you must work on yourself. If you cannot trust a man simply because of his genitalia then you have issues to deal with. Women can be just a mistrustful and keniving as men. I get into this "men suck" debacles with my office women almost daily.

What is it you are looking for? A sex-fling? A serious partner? An open life? Sex is one thing but if he has already commited to you and wants to hang out with others, then he's playing the field. If you are ok with this, fine. Otherwise look for someone else. You have a great responsibility in your life to focus on. I wish the best for you

A year apart isn't anything to worry about. Usually when you're dating someone, the only important factors for getting along are goals, maturity level, and common interests.

You shouldn't allow yourself to be a backup plan, and it's not very nice of him to inform you that he's making a choice. Sounds like he's playing the field.

Hmm this guy seems like the player type. I mean he has already slept with you and now he is deciding whether he wants to go out with you or not?! That's retarded! But I'm sure you already know what kind of person he is already so it really depends on what you will be expecting from him if you guys do go out. A good tip is making a check list of things that you want in a relationship and then see how well he does on the list. Hope this helped