You're the one who said you are depressed . . . and I think you are right about that. Anyone who's been cheated on in a relationship will be very sad about that, but not everyone will become truly depressed by that experience. You may have two problems - a relationship problem AND mental depression. The two problems might be feeding onto each other and aggravating each other.

Most people find it difficult to be in a relationship with a person who reacts to adversity by becoming depressed. People prone to depression tend to get very depressed when someone fails them in an important relationship. So the two things feed into each other. It is up to your boyfriend to do what it takes to win back your trust, if he is capable of becoming really worthy of your trust. Maybe he's not, and then you might need to end the relationship and move on. I don't know.

If the relationship ends, or you decide to end it, then you'll be very sad for quite a while. But if you see yourself being eternally depressed, unless you can get back to a good relationship with this particular guy, then you have a depression problem that is independent of what goes on between you and him.