You're doing the right things for the right reasons, and part of doing the right things for the right reasons at times like this seems to involve feeling guilty/self-doubting/self-loathing as hell about it, so believe it or not it sounds like you're actually doing OK. Which sucks, but there it is.

Setting an upper limit is definitely a good thing to do, and it's likely your partner can help you a lot in talking through different scenarios and contingencies to define some objective thresholds and well-defined actions once you hit one of them.