IMHO, ANY sustained cardio exercise will help out...cure? Certainly not, but it's proven, and I believe it wholeheartedly, that moderate exercise improves mood. Asking whether or not
cycling would help in here is like asking crack addicts if they like crack.
But seriously, try a bike for a while. If I were you I'd find a therapist or counselor to talk to...doesn't have to be deep or heavy, just someone to explain your issues to who can lend an ear and maybe provide unbiased suggestions, ideas, and/or support.
Hang in there, and if you keep on the bike long enough, c'mon back and join us loonies here...we all have 'flictions of a different sort
.