It's perfectly normal to feel upset and hurt. After I went through a similar experience, I remember expressing my frustration in prayer that I was still so angry with that individual. The feeling I got in response was that it is okay to grieve and be upset. We constantly hear messages of forgiving and loving everyone, even those that hurt us, and I think that sometimes we assume that that means we have to unconditionally love them right now. I used to beat myself up for not being able to fully love this individual. But the way I see it now is forgiving others means we will not try to keep them from happiness. Do I want to stop that individual from making it to heaven? No! But do I want to spend time with him in heaven? Absolutely not! And that's okay. The main reason I believe we need to forgive others is so our lives are not hindered by our anger for others, so that we do not become bitter and withdrawn. Grieving is normal. Getting upset when you're reminded of him is normal. But as long as you aren't intentionally holding onto that anger, as long as you do want him to be happy, that anger will fade.
To move on, find things to do that don't remind you of him. Write out all your feelings, tell your friends how you feel, and then try to avoid talking or thinking about him. It helps to get those emotions out, but to continually dwell on them will just make them worse. Find others to serve. Get a new hobby. Of course, you will still run across those things in campus that will remind you of him, but if you don't allow yourself to focus on those, you'll find those feelings will lessen in time.
If I may be so blunt, there is nothing wrong with you, though there is probably something wrong with him. To feign interest in a girl while dating another girl (or, in the case of the individual I knew, feigning interest while leading on his ex-girlfriend—maybe our "friends" gave each other advice) requires a special kind of low. If you're like me, you'll keep asking yourself, "Why was I so much of an idiot? Why didn't I see those warning signs? Why did I let myself get drawn in?" Let me reassure you: YOU ARE NOT STUPID. YOU ARE GOOD ENOUGH. Guys (and girls) like that have been tricking good, smart, wonderful women (and men) throughout history. If good, smart, wonderful people had an inborn superpower to recognize and avoid those kinds of people, we wouldn't have half the literature we do today. You are good enough.
I nearly wrote "one day you'll find a man who will show you just how incredible you are." But then I realized that that is judging your worth off of what a man thinks, which is absolutely not true, because you are incredible, regardless of what any man may think of you.
Finally, let me assure you that things do get better. They get a lot better. It may seem hard to trust others now, and you may feel unwilling to open yourself up again, but it is always worth it. Because of this experience, you will be able to relate to and help others who go through similar experiences. I can promise you that your pain is not for nothing. It will shape who you are, give you better opportunities to serve, and will make you appreciate your friendships and future relationships so much more.
-guppy of doom