How do you grieve when you don't know what to do?

Everyone grieves in their own way, and their own way, but I can say there is not much that is worth wrecking your own life. You need to think of what that person would want you to do, and I am sure it is not wreck your life.

Spend some time in solitude letting your memories of her fill your mind, maybe having an imaginary conversation with her (or speaking your heart to her spiritual presence, if you like). Tell her what you told us - how important she was to you, how you remember her, how you felt toward her when she was alive. If there is anything you wish you could have said to her, tell her now. You don’t have to believe or disbelieve anything to do this. It’s only a “real” conversation if you want it to be. Just let your attention rest on her lingering presence within you - because that presence is real to you - and notice the thoughts and feelings that pass through your mind as you do. It doesn’t matter whether or not they seem to you like what you think grief is “supposed” to be. As Chris said, people grieve differently from one another. Feelings that don’t come now may come later when you are ready, or they may be there now in ways you do not yet recognize.