If you are prone to depression, it seems to me that your pattern is to internalize and retreat when angry. Not many places to retreat on a boat!
On the other hand, cruises are a great way to break a cultist away from their old habits. The natural personality starts to emerge. By carefully staying away from religious topics and frequently reminding your sister and mom of their authentic interests and desires, you might end up with two very different people on the cruise!
At the very least, the three of you may conclude that you don't want to lose each other. That is, if you have anything at all in common.