Who cares if she gets upset?  Your life is hell thanks to her poor choices, coddled criminal son.  

The dogs are the only innocents in her side.  They are doing as they’ve been allowed.

Does she work? Where is she getting the payoff money from?

Can you move out and get your own apartment?  I’d tell her she has until x date to get her criminal offspring out of your house, or you will be (moving or starting an eviction process for both of them if the house is on your name alone).

Id also go see several good divorce lawyers now.  I have no idea what the rules are on annulment, but I’d look into that.Protect yourself, because it sounds like you are running a huge risk living with this loser and her kid. 

I know you love her, but as you’ll see over and over on here, that’s not nearly enough.

If you're so miserable that you dont want to live than please seek help and leave NOW. This is not healthy and its affecting you mentally and emotionally. Just the thought crossing your mind are red flags and you have to consider yourself first. To heck with how she will feel, you are priority and you are what matters. If she wants to enable a 28 year old man that's on her but under no uncertain terms should you suffer because of it.

Please get help and do what is in your own best interest.

You are in a crap situation. Your wife isn’t the person you’re in love with. Unless your plan was to love an enabler with a vicarious drug habit. 

Its time for you to put up boundaries and for your wife to decide if she’s inside or outside of those boundaries. I would start with separating finances. 

Quite simply you need to end this mistake of a marriage and go back home. We all make mistakes it's okay. Just don't stay and ruin your life forever.

Re-read your original post and ask yourself what advice you would give the person who wrote it. You know what to do.  

Move on.  Abandon this tragically flawed shallow and polluted gene pool and never again sacrifice yourself on the alter of SParental martyrdom.  You cannot make a life with a person who does not make you and the relationship her priority.  Many people sacrifice themselves to fix a rescue project.  It rarely is a successful effort.

Said like a real man Rags...LOVE IT !!!

I find myself wondering if this situation (ie SS living with his mother) was in place when you moved in with her. If so, this was a very bad choice on your part - as you are now realising.  Maybe a part of your current despair is that you now know this?  Regardless, your inner self is screaming at you that this is all wrong - you need to take decisive action to rescue yourself from this awful situation.  

Your wife is not helping her son, she is enabling him, and the awful cycle just rolls on indefinitely.  Time for her to implement some tough love.

I'm a little confused - OP, didn't you just move into this situation knowing the kid was there? Or did she say he'd move out and he hasn't?