hi Oxo, and

you sound exhausted, and pained.
there are a lot of issues here. they did not develop over night, and they will not be resolved over night (besides, you dont want to rock the boat too much too soon). but there is certainly hope.
i suspect that the cancer diagnosis was a catalyst for things getting worse. facing mortality is scary for anyone. with someone with deep fears of abandonment, a person in that position would be hyper in tune with the waxing and waning of your attention (even to a distorted point), and its not uncommon that the reaction to that is to lash out.
often times, the first step in improving a relationship is to stop the bleeding. theres a lot of conflict and a lot of resentment here. we have two tools here (they very much go hand in hand) that can go a long way toward stopping the bleeding and the conflict, and begin to take off some of the tension.
https://bpdfamily.com/content/listen-with-empathyhttps://bpdfamily.com/content/ending-conflictadditionally, youre going to need a strong support system. im glad you reached out to us, and i encourage you to stick around and involve yourself closely with other members, and in learning the tools.
the sleep deprivation is also concerning...we arent at our best in those circumstances, and its far harder to think in terms of stopping the bleeding. is this a recent development?