The whole 2 years we pretty much argued all the time she always said one day I'll be left on my own and I'll have no one.
I used to hear that from mine all the time, especially during breakups. Seems to be right out of the playbook. That was her
projecting her fear of being alone forever because she probably knows it is in her nature to eventually
drive people away. You have a right to be angry at her, but I think over time you will also become sad for her and what she has to live with. Not to say you won't still be angry.
Your focus should now be on yourself,
your recovery. Why? She is jumping from one relationship to another with no indication she will ever change that pattern. You can't control her (and shouldn't). You can't fix her (only she can fix herself, with experienced help of course). If there was hope for the relationship and she was making real progress in intensive therapy for months and years, then you could 'support' her as she improved. But unless she's in meaningful therapy and improving, the only person you can change is... .yes... .yourself.
Consider
counseling for yourself, to get objective assistance from someone not emotionally involved in your life. You're on the inside looking out, wouldn't it be nice to get help from someone on the outside looking in? Hmm?
Illustration... .I wasn't a bad kid but when I was a kid we had chickens and I recall a few times I picked up the roosters, tucked their heads under their wings, looped them around in my rotating hands for several seconds and then set them down and watched them stagger around for a few seconds until they got their balance back. Well, right now you're staggering around from the huge impact of a two year dysfunctional and unhealthy relationship. Betrayal, two-timing or three-timing, constant lying, conflict and who knows what else, you really were turned upside down. Seen that way, getting some counseling to help you recover and get proper perspective sounds like a good idea, right?
