Husband having male fantasies

Married for 6 years, together for 9. Prior to marriage, he was engaging in online messaging with other men and women and admitted to a porn addiction. We went to couples therapy, individual therapy and put in the work. I thought we’ve been good, building the trust back year after year. This past week I could feel something off. The pit of anxiety, the ache in my bones, and I asked. He’s been continuing to message men on/off this entire time. Says it’s a fantasy to be fucked by a guy but he says he can never go through with it bc he’s not attracted to men. When this was brought up in the past, I bought a strap on and some butt plugs and we explored his kinks. I don’t care what gets him off, I’m open and willing to try most things. I do care that here we are nearly 10 years in and he’s still repeating a pattern of triggered by stress, watch porn, then messaging guys. Those guys have feelings too and I actually felt bad hearing this that my husband leads them on too. I’m numb. I don’t know if this is a trauma thing he can work through or a denial thing he won’t ever overcome. It’s not the most exciting, over the top marriage but he’s shown me love, supported me/kids (16/20) and I do think he truly loves us. Can a fantasy stay just that? I’m just gutted… this fucking cycle has been on repeat and now I get why my gut has felt this. I just kept telling myself it was residual anxiety from the past… ugh. The betrayal is the lies, deceit, repeatedly crossing the boundaries we set ( I said porn was totally ok, I watch occasionally too, but no human interactions).