I don't know what to say about your relationship troubles -- I've never been in one -- but I have learned a trick for managing suicidal impulses. When I feel the urge, I just put on some dark, introspective music and let it blast me into submission. After a few tracks, I'm too weary to actually follow through on the impulse. It's not something that requires an extraordinary effort, either, so it's become my default response to suicidal urges.