Okay...

You are not weak - you are human. I know guys think that they're not allowed to cry, and if they do then they're wussy or something... totally not true. If it happens, then it happens. And you have an awful lot to be upset about right now.

You are not a waste of time, space, or energy or anything like that. You will get through this... but it takes a lot of time. Have you been able to talk to a counsellor about this or anything yet? Do you plan on doing so? (I recommend it, it has helped me on numerous occasions)