You should read up on child sexual development and recognise that what you did was in no way unusual and not at all harmful. If I understand correctly that you snuck a peek while she was asleep and she doesn’t even know, then how would it harm her? You were a child, and curious about something you didn’t know anything about. Yes, sneaking a peek was naughty, but are you really going to keep torturing yourself, at 24, for being a naughty child one night when you were 10? Good grief! All children are naughty sometimes. Even the saints were occasionally naughty children, I can assure you.

I don’t see how you could gain anything by apologising, especially if you’re not sure how she will react. It sounds like your family perhaps places a lot of importance on appropriate sexual behaviour. What does your mother think of this, does she think it’s a big deal? Because it’s really not.

Is this issue the only cause for your anxiety/depression, or were you feeling depressed before, and have you picked up this old hoary chestnut because you were looking for some reason to be upset? It may sound weird, but when you’re depressed, your brain can sometimes hunt around in your memories for things to feel bad about so that your feelings and thoughts are on the same line.

I hope you’ll come back and tell us more about what’s going on, because it really sounds like you’re making yourself miserable for no reason.

The best way to get out of it is step by step. And yes, I think the problem is your unhappy mental state and your isolation (they re-inforce each other), not this “incident” from over a decade ago, which is really no big deal.