@Toik,
First of all, I'm sorry to hear that you and your best friend are having a hard time. When feelings get in the way of a close friendship, it's never easy, especially when the feelings aren't returned. It sounds like his actions and the changes in your relationship since you tried to get romantic with him have really hurt you.
Tell him how you feel in a clear, non-threatening way that doesn't push him around. Try making some rules about what you need to keep the friendship going, like more open communication or some time alone to figure out how you feel. It's fine to take some time apart and figure out what you want from the relationship.
Don't forget that relationships, whether they're romantic or not, involve two people. If he's not willing to compromise, it might be time to rethink your friendship. You deserve to be with people who make you feel good and help you, and it's fine to let go of relationships that aren't helping you anymore.