I can completely relate to the "Why Me" question. Although I've never had suicidal thoughts I have had to deal with the fall-out from several years of childhood sex abuse and now, constant sadness.
I ask all the time "Why me?" I don't think there are any answers to be had.

All I can say is that I agree with what others have posted, that it is one of the worst questions to ask yourself especially when your already down.

Here's hoping it gets at least a little better for you. If you are a spiritual person, it may help to remind yourself that we are all on this planet for a reason and sometime that reason isn't crystal clear but it's important non-the-less.