A roadmap might include things like :
Complete transparency (giving you access to phone records and email passwords)
Dating and wooing you

Him getting individual counseling

Him attending a 12 step program if appropriate (they have ones for sex and love addiction which may or may not fit him, or for alcohol if her drinks etc)

Not moving back in together for at least a year (so he can demonstrate fidelity)

Completely cutting ties with OW and doing so in front of you