It's a hard day for a lot of us, I imagine. I can't say I have any advice, but I can say that you're doing things differently this year, because you're here, and you're trying hard to become a better, sober person.
I wish you well, Olaf. Be kind, to yourself and her, as best as the day allows. It is, after all, just another day. My wife and I don't really do much around Valentine's Day - not for lack of love, but just because so much societal/commercial emphasis is put on it. Flowers and candy because Hallmark says so? The trick is to express love on any given day.
Just do you best, and don't let her expectations dampen your attempts to be kind to both of you.