Welcome to HealingWell and the Depression Forum. I am sorry you are in this situation.
To be very honest I think you need to find a good therapist that will help you sort out your issues.
First you need to cut your ties with your husband as you cannot make someone stop using drugs. You posted " man I still love"
You have moved into a relationship with someone that you do not seem to be happy with and he sounds immature as you have stated. I would agree with you, a 22 year old male taking on another man's family including having his SO's Father in the picture would take a very mature person, one that loves you deeply.
Do you love this 22 year old man? Many years ago I was in a position similar to yours so I can empathize with you. Please do not think I am judging you in anyway. It sometimes helps to get the perspective of one who has been there and can look back and see the poor choices made. I made many but in the end I did meet a wonderful man who married this divorcee with 3 young children and he was only 23 to my 24. We have been married for 37 years now.
Good things are in your future.
I wish you peace,