Supporting my partner with a PA

Me and my partner have been together almost three years now, and have lived together for a year. He has struggled with his mental health for some time now and I’ve grown more concerned as he’s withdrawn from me gradually over the last year and a half. He is a very private person anyway and our communication on both sides has been shocking, I’ve also been struggling with my own mental health during this time. I grew increasingly suspicious and to cut a long story short I did some digging and found out he is a PA earlier this week and has been throughout our entire relationship, for the past year and a half he has been paying for webcam girls and reached an all time low when a couple of weeks ago he visited a ‘masseuse’ and I then found out.

I want to stay with him, I love him more than anything and when things are good they’re great but this has all been such a huge shock to me and I’m finding it very difficult to process and was hoping to hear from anyone else in a similar situation. I want to support him, he said he has tried stopping multiple times throughout our relationship but always relapses when we have sex so I’ve agreed that we start by trying 3 months total abstinence. He’s self referred for counselling, has started taking antidepressants, has contacted his local SAA and wants us to try couples therapy. All of which I want him to do and fully commit to but I’m so scared he relapses. He said he has never been successful before because I didn’t know about his addiction and he didn’t know how to tell me that we couldn’t have sex for three months.

He has said he is happy to do anything I ask of him and seems to be very focused on helping himself as well as our relationship. He’s started leaving his phone out when he goes to the bathroom (this is where he would usually do it) and going to bed/getting up at the same time as me. He’s said he will show me all of his bank statements and we went through the transactions together on the website he used and added everything up. He’s also deleted all social media and I’ve written him a letter which he has said he will read if he starts to struggle. We have been talking about it A LOT. We’ve never really sat down and had deep, meaningful conversations but the past three days that’s all we have done. He has also taken some time off work to be with me as he says he’s worried about our relationship and my mental health. He uses this website for support and has been encouraging me to do the same so I’ve been trying to educate myself around this as I didn’t know much about it. He also admits that what he has done is cheating and he seems to be showing a lot of remorse, crying a lot and the past three days has seemed a lot calmer and more mellow.

I’ve made it clear that if he relapses or I find out he’s been lying to me again that is it and I will leave.

i have a few questions. Do these boundaries sound ok? Should I forgive him if he fully commits to everything he says he will? Is it possible that he will stick to it this time now that I know? Is there anything else I need to be doing?