First of all, I am sorry you were "screwed over." It happens to a lot of people who trust somebody with their heart, only to have that person be a total douchebag and stomp all over it. You can't control or predict how people will handle being told "I love you."
It's understandable that you're angry. I would be, too! Anybody would feel bitter, betrayed and furious over what happened. You have every right to be mad. I also get that you think love and romance are total bull-crap ideas, because look what happened to YOU. Again, you're completely within your right to think that.
It does take a while to learn to trust people with your heart after getting "screwed over" in any way. But believe it or not, there are still people out there who are trustworthy. You were unlucky enough to meet someone who wasn't, and I know it's caused some damage. You can tread as carefully as you want for as long as it takes you to get over the hurt you're feeling now, but do remember that not EVERY guy or girl you meet will screw you over. Really. Just because one person did doesn't mean the next person will, or the next.
Real love still exists. Some people find it on the first try, and some people have to look long and hard before they do. Unfortunately, if you really want love, you have to use the "trial and error" method--getting to know someone, seeing if it works out between you two, and accepting that if it doesn't, it may hurt to say goodbye and have to start all over again.
The best thing to do is learn from this experience--make a list of all the things this person did to you that hurt you, and remind yourself to watch out for this kind of behavior in someone else. At least you're now wiser for the experience!
If this person really hurt you the way you say, maybe they never loved you as much as you loved them. That's not your fault. You deserve to be with someone who will return your feelings, respect you, and never intentionally hurt you. That is real love.
I hope this is some help. Sorry for your heartache.