I am so sorry you are going through this. I cannot even imagine the stress.
With H, it's not a slip. He is using. Now, you have to cope with that fact and decide where you want this to take YOU in the future. Do you have a counselor? That would be my first recommendation, to find a counselor who specializes in helping families deal with addiction. For YOU alone, for the support you need. There are also NarAnon or Celebrate Recovery meetings that may help you. There will be people there who can relate and give you face to face support.
Big hugs to you.