He keeps cheating

My partner (37m) of almost two years and I (37f) have an open relationship, yet he keeps lying and cheating on me.

The rules we’ve set about open relationships are we talk about our other potential partners before we go on any dates or choose to sleep with them. We’ve established a primary partner between us. He has been with other women, which has been hard for me, but when he opens up to me and tells me who he’s been with, it opens up our communication amd brings us closer. I haven’t had any interest in sleeping with others, but it’s been offered to me by strangers many times.

Last year I found out he’s been texting and fucking his ex girlfriend, who he cheated on because they weren’t in an open relationship. We got through this after a lot of ups and downs and me leaving him for a few months. But in the end we agreed that what we have is special and wanted go work through the lies and cheating. Which has been hard for me, because my family and friends found out and aren’t supportive of our relationship.

Now, 7 months later. We’re cleaning his room together and his ex girlfriend’s shirt and pants falls out of his laundry. Clearly she’s been there in the last few weeks, and he knows what my limits are with her. His go to was to lie to me again and claim it wasn’t hers. But eventually he told me the truth. And it is her clothes. Yet “we” decided we wanted to move on together and leave that in the past.

I’m struggling with this in a lot of ways. First I feel like I’m falling further away from him, and I’m falling out of love with him. Mostly because I can’t believe him anymore. Also, I’m struggling because knowing him, the more someone’s says not to do something he wants it even more. Like someone tells him he will never be a homeowner and then he will work his entire life to make sure he is a successful homeowner—aka I feel like I’m pushing him into her bed because I’m saying she’s off limits. Honestly the fact that they were once in love doesn’t bother me as much as how horrible and manipulative she is. And he loves to feed his addictions.

I’m struggling as someone who’s supposed to be in a polyamorous relationship with a liar who is addicted to lying and sex. I’m struggling why I should allow myself to keep going back into his life and worried that my entire relationship is a lie with him. And my concern is I’m bending over backwards to accommodate for him and I’m losing myself.

I guess what I’m asking for is your advice for folks who are in open relationships with people who cheat, who are insecure and are prone to lying. What advice do you have?