Nia354, you're in a rough spot, but there is hope.

"Involvement in an unhealthy drama triangle is not something another person is doing to you. It's something you are doing with another person or persons."
What role do you usually play/are you asked to play on the triangle? Victim feels powerless, Rescuer feels compelled to fix, Persecutor blames.
What roles do your partner and the other woman play? Can you give us a scenario so we understand how it plays out?
If you haven't already, check out our article on the Karpman drama triangle.
https://bpdfamily.com/content/karpman-drama-triangle