LBM, just wanted to say it's going to be ok, no matter how it turns out.
I don't want this to come off sounding know it all or belittling, because it's so not meant to be.
But I remember what head space I was in when my son was 2 months old. There are still hormones, some unbelievable mother lion stuff going on and just trying to adjust to life as a mom after 39 years of SOOO not being a mom.
It's rough. You are sleep deprived, too.
This couldn't have happened at a worse time for you. Just make sure however you decide to handle it, that you don't make any big decisions without having had some sleep, a meal and some time for yourself. Just as your friend/exfriend isn't herself right now with everything that's going with her, you aren't yourself either.
I'm not saying cut her a break or let it slide. But how you handle it or think you should handle it might change depending on how much you've been able to take care of yourself and how much rest you've gotten.