I'm super short on time here so I'll just chime in with a quick
Did she get angry with Girl B for making out with you?
This relationship reminds me of my marriage! I eventually saw the red flags and ran! Not far since we have children together but I still ran.
Was she testing you to see exactly how far you would go?
She DID send confusing messages to you at the party. "You're ignoring me" is pretty clear but then inviting Girl B to share your bed??????
Gotta run, more in depth tonight hopefully.