There are days when I read this forum and think that I could have written almost every post myself. Your post is one of them.
You are in your full right to cancel that meeting if you feel it's something he manipulated you into saying yes to when you really don't want to.
I wanted to say that first, because I've been exactly there: Agreed to a meeting "because we need to be on amicable terms for the sake of the kids" only to realize that, wait, he's just pulling me in again -- this is not about what the
kids need or about what
I need -- it's about
him, again.
I can tell you what I've done: I have limited our contact to e-mail, other than in emergencies. Now, he and I define emergencies differently -- for me, that would be "our child has a gaping wound and I'm in the ER," for him it's "DD can't find the charger for her phone"...
I have told him in no uncertain terms that I want
minimal interaction between us. I keep my e-mails very brief and to the point. When he goes off on a rant and accuses me of being the cause of everything evil under the sun, I ignore it. I've also told him that if the communication veers away from things pertaining to the children, I will hit delete and not look back -- so if he has important things to tell me, stick to that, or chances are, I'll never read it.
(I don't delete, of course -- I archive those rants.)
I've had really good counselors who have been good at catching me when I fall back into the enabling codependent behavior, because when you've lived like that for a long time, it's very easy and natural to fall into the "oh, he needs me, of course now that I've been the mean 13itch from he!!, I have to run to his rescue."
As someone here said -- if a guy needs rescuing, call the Coast Guard.
It's not easy to find your own footing and your own boundaries, but you can, and you will -- we can and we will -- one step at a time.
And I agree with every word of what Ceridwen said.
I don't want to be his friend and I don't want him to be mine, not at this point, I know all he could handle is a false friendship entirely based on his needs and perceptions, and that if I put a foot wrong in his eyes (any boundary enforcement or stating at all) he swings back to verbal abuse.
All I want is the basic civil interaction I would have with anyone else, a sort of business acquaintance: the business being raising our children. I don't want to watch a movie with him (we don't like the same movies anyway), or chat about what he's been up to over the week, or how tired he is because he "had to" sit up til 5am playing computer games online.
I don't divulge any info about my life (he doesn't ask, except to try and find evidence for the boyfriend/s that he is convinced I have), I try and limit contact, because the more time I spend in contact with him the more I have to repeatedly enforce boundaries and that sucks my already depleted reserves of patience/time.
I rarely bother stating my boundaries to him, as they always go unheeded, or he tries to argue me out of them: I just cut short the contact. My boundaries are pointers for me which cut down the crap in my life, not rules for him to live by; he's not a toddler, it's not my job to teach him how to behave.