I advise against setting your date even remotely near to a special occasion or holiday, especially Christmas. Many people close to you would associate this holiday with your passing and it may make the holiday hard to deal with or completely unenjoyable all together.
If you don't care about the impact that this will have on people, though, then I agree that it would be quite poetic to ctb on Christmas because like you said, it would be a gift to those who did you harm and hopefully they don't take it the wrong way or I assume it won't end well, just like in the first scenario where they associate the holiday with your ctb.
Also, don't talk like that about yourself. If anything, I'm a piece of shit and you're far from that, trust me.