Mentally, what I see is that you set boundaries for him, not for yourself, and expected him to follow them.
Boundaries are things that we set for ourselves, that belong to us. Instead of saying a boundary is "He will not drink" - a boundary for YOU is "I will not have a relationship with someone who drinks." Things you talk about with your partner about how you would like them to behave are "expectations" and not boundaries. Expectations are things we have no control over - we would LIKE our partner to do certain things and we communicate this - but our partner may or may not do what we expect. Often times, especially when dealing with alcoholics/addicts/etc, expectations lead to disappointment.
Your boundary, on the other hand, is something you DO have control over, because you are only looking to control your own behavior. If your boundary is "I will not be in a relationship with someone who cheats on me" and your partner cheats on you, then YOU control your own behavior, honor your boundary, and leave the relationship. It puts the power over your life into your own hands.
I hope this makes sense. What are YOUR boundaries, and how will you honor yourself both in the setting and the enforcing of them?