Need advice from reformed cheaters or reformed substance/lifestyle addicts of any kind

I am female and 27. Relationship is 2 years old, with a 7 month old son.

My partner (M, 22) has an addictive personality and complex PTSD.

We have great communication, but he was still holding onto a lot of fear and wasn't being as open about his darkest thoughts as he could. I've shown him before that I can forgive him when a similar incident occurred, but only now does he realise the depth of my commitment because he didn't expect me to stay when he made a mistake again 18 months later.

He has been unfaithful, not because he's unhappy with his life but because of constant negative self talk, telling himself me and my son are too good/perfect for him, and because he was drunk. Not people who are better or hotter than me or that he even desires. Just doing it literally as a compulsive shitty behaviour. Typical self sabotage stuff. He doesn't have 1 addiction, but he can switch between binging many things (aka. Addictive personality) such as drugs, video games, drinking, gore/banter/porn group chats, or even a boring clicker game on his phone. Then feels guilty and hates himself more for neglecting his family. Anything to get that dopamine rush and distraction from his constantly racing mind and negative self talk.

Anyway, he knows willpower isn't enough and he is going to get therapy, as well as as the relationship counselling we are booked in for.

I can forgive him. I am supportive. We talk about things openly and have a mature relationship without petty drama.

He has told everyone important to him/us he will never drink again (He doesn't drink much, but when he does he loses inhibitions more than is standard, and has personality changes. He also comes from a family of addicts and abusive relationships).

We are both cutting down screen time and generally avoiding time wasters or maladaptive coping strategies.

He has also told the people closest to him what he has been like and who he wants to be instead, so he can be held accountable and be better supported.

It was a huge deal for him and he told me he feels better already knowing that it will prevent him trying use other people to enable negative sides of him anymore, and also that they have shown support and respect in their responses.

I work in psychiatry and am up-to-date with trauma-informed care, why his brain is different to mine from an abusive childhood and also because he is young, and the fact that recovery from any addiction involves more mistakes and requires support and openness. I don't need advice on that stuff. I just wanna know what works to keep you/your partner/friend "in recovery", in a practical and also emotional sense.

TLDR; My question is very specific:

Please tell me what your action/safety plan is, if you were to feel yourself slipping into negative compulsive or addictive behaviours.

Have you ever had to tweak it?

What did and didn't work?

Edited to add: We have done drugs together in the past, we have a great sex life, we both drink occasionally, we don't spend much time apart, etc. I am stopping drinking as a sign of support and I haven't done drugs for over 18 months. We own our own home and have a stable life in general. He can't go to AA here because his mother attends and she is obviously a huge trigger in general and already bothers us a lot, lol.

P.S. This is my dominatrix account and my post history only contains random question answering, Findom/fetish ads and PORN, so don't go through it unless you want to see it. And don't inbox me about it, like every other guy does when I post unrelated stuff. Thank you.