DM has anxiety and has relied on me as a shoulder to cry on since my early teens. She's a very dominating character, her erratic mood swings have always had a big impact on me, but I've never challenged her, and this has been compounded in recent years as she was widowed suddenly and now cares for her elderly parent so I feel I can't challenge her as she's lonely & stressed...however...her erratic behaviour is now starting to impact my DC & I'm wondering if the time has come to either challenge her or withdraw. So for example, we won't see or hear from her for weeks, with my eldest asking where she is, then she will turn up without warning (letting herself into my house with her key) and either be totally wiped out and cold with my DC, which completely confuses them, as other times she will be bouncing off the walls, play the clown, wind them up into a frenzy, then leave. On top of this, I feel there's a lot of subtle undermining of me as a parent going on in front of DC. When she's here, I feel tense and stressed and relieved when she leaves. But but but...she's alone and coping with a lot on her own, should I really confront her? I feel like life's too short to argue but I also feel increasingly angry at her behaviour. WWYD?