I don't know how to be supportive. Advice, please.

My fiancée is addicted to sex and pornography. He fetishizes infidelity and prostitution, probably as a result of his 20 year addiction. As you can imagine, this has caused a multitude of problems in our relationship. All of this came to a head last night in a long, drunken crying session. We decided together that his journey would begin today. He's doing Hard Mode until sex feels healthy to him, and then Standard for the remainder of 90 days. His journey starts today.

Now, I don't know how to be encouraging and supportive without being controlling, policing his actions or being jealous. Do any Fapstronauts or SO's of Fapstronauts have advice for someone in this particular situation? Any help would be greatly appreciated! Thanks in advance!