What is your relationship like with her? How much do the two of you spend time together. Just you two? Maybe all three if you should talk about this. He is obviously not going to follow YOUR rules, so why not work on boundaries together. Negotiate. Even if you can compromise for now even that might mean change for the better for all of you.
Have you ready some threads here on "lessons" and "foundations?" Both can be found by doing a tag search for those tag words. Your partner and this woman might benefit by reading them too.
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