You're building up a small issue, tying in larger things that to me seem less related. Your issues with Andy aren't your issues with your kids. And whether you celebrate Christmas with your XH and the girls is separate from whether you have Rs with any of them.
I think you need one safe person with whom to talk and process your experience. Whether its your former life coach or a new therapist, this depressive funk seems to be worsening for you, Hon. You're too bright a woman to be thinking in this all-or-none fashion, so that suggests dep. I liked Ellie's idea about meds. Please consider taking them, for a short round at least, ~ 6 mo, to help you to dig out of this hole. I have taken them in the past for the same reason, relying on my cognitive-behavioral changes to keep me moving in a positive direction while weaning off them after several months. I'd ask your doc to consider a newer med that addresses both serotonin and norepinephrine.
I know this may be an argument against your depressive thoughts rather than me dealing with my everyday JO, but IMHO, it is not possible to severe a mother-child bond (or a father-child bond). You may feel separate, and have fewer thoughts/bonds about or with them, but Jo, they will experience a screaming, gaping wound of the absence of your love - for as long as you stay away, up to a lifetime of this pain. Sure, it'll numb a bit over time, but it will flavor all of their Rs with other human beings. For that reason, act slowly and in a well-thought-out manner.
The saying goes, "A loving mother loves herself." So if you need to stay away and not let the a$$hole manipulate you into something you're not prepared for, than stay away for Christmas. My view is that this may be your emotional side telling your cognitive side that it needs to be taken care of and fed. Don't ignore that. Seek counseling and meds, and douse yourself in self-love. Only then will you feel less depressed and more able to love others, in particular your girls.
In the long run, you will be teaching them a very wise lesson - that to love another, one has to love one's self first. Attend rather than ignore your messages to yourself in the moment, and like any great DBer, plan for the longterm future by setting up goals for yourself to get out of this funk.
