Here I am commenting again before reading the whole response. I just want to say SEE!!! I'm right!!! Lots of people these days think it's fine and dandy to have this kind of friendship and they pay no attention at all to boundaries. You don't get to be the kind of friend who talks every single day to a man who has a girlfriend or wife. You just DO NOT GET TO BE that friend. Frankly if you want to be in that situation you should talk to a therapist about your sibling rivalry issues.
Does it ever occur to anyone that they don't need their parents to understand or accept their anger and criticism? If your parent is critical toward you as some sort of defense mechanism, how about this? How about you don't put them on the defensive. When you become a parent, if you aren't already, you will make mistakes, you might fuck up a little or you might fuck up big time... consider how you would react if someone expected you to acknowledge and apologize for fucking up. You can let go of your anger at another person by accepting that not one of us is perfect, not one. I think part of the problem is that we live in such a vengeful, vigilant, punishing society. If we feel pain, somone has to pay. Stop making your parents pay, just stop. Yes, you can be distant because talking to them drives you crazy and gives you PTSD, that's fine. Confrontation about old issues is pointless and will likely wake up the defensive critic that lay dormant in them. The problem most of us with crappy parents have, really, is that they have a vested interest in thinking lowly of us to aleviate their own guilt. Simply do not listen to that shit or buy into it, recognize it for what it is... a salve. Waking up that guilt does not help your parents to behave in a more endearing way toward you.
It's possible that the letter writer is depressed but it's also possible she has a different or additional problem going on. ADD/ADHD often go undiagnosed in females and they can look different in young women than in males. Based on her writing style, the fact that she seems to be lacking a sense of herself and is low on executive function, I think it's worth looking into the possibility that she has ADHD or ADD or possibly some other brain issue going on.
And, my comments are redundant. I should have read the answer before commenting. That said, I still think she should leave this guy.
@FloffMe I think it's possible to share joint custody of a kid and maintain a great deal of distance with the other parental units for the sake of sanity and avoiding drama. I also think it's unnecessary to keep those ties over a pet so if someone is doing that, perhaps there is another motivating factor.
I also want to politely suggest that the letter writer is hiding in this drama from what is possible in her own life, hiding from her true self. She needs to go out and live a meaningful life.
My instictual answer to this, only reading the question so far, is leave and get a life of your own. This relationship is triangulated from the start and rife with drama. GET OUT!! If the ex is a crazy bitch and he still has contact with her, he has his own issues and he might even be using his ex as a power play with you. RUN!
Heather, I'm absolutely in love with you after reading all of that. Let me know if your SO is hit by a bus. You never know, maybe my madly in love husband will suffer an amnesia attack at the same time and wander away from the house. And also, I'll become a lesbian.
"You're hunting a very small group, that's all. Your target demographic, it's small. There's more than one of them, but they're not everywhere." I like the way this is phrased. I used to tell people that almost everyone they meet will be a complete waste of their time. "Learn to say the word Next." The way Polly says it is so much nicer.