Tcrose, I am very sorry you are in the situation you are in. Your son has effectively driven a wedge between your family as he manages to hold you hostage at your mother's and be disrespectful and rude. The longer you put up with this bad behavior, not only will it continue, it is likely to get worse. You are in a difficult place, however, you should not allow your son(s) to dictate the lives of you and your husband, all you do is send the wrong message that this is okay. What you are doing is enabling him.
Many of us here have or are facing similar issues with our adult kids, it is an extremely hard place to be. Many of us opt for some kind of professional help. Since your sons are using drugs and drinking, you may certainly benefit from al-anon meetings, 12 step family groups or private therapy. You will need help to make different choices which will be healthier for your husband and yourself and you will clearly require help to set strong boundaries around this kind of behavior. If you continue to permit this behavior, this is what you will live with for a very long time. Neither of your sons has any incentive to change.
Of course you are worried about your sons situation, that is natural, unfortunately you will need to override that worry and in my opinion, give your son a clear ultimatum and stick with it...............you go back to your husband, he vacates your mothers and finds a job, a shelter or the streets, but this behavior cannot continue. Those kinds of hard choices absolutely require professional help because as you can see, left to your own devices, you will permit the behavior because of your fears about the outcome for your son(s). Unfortunately, as we have seen here many times, the issues with our kids rarely if ever gets any better until we make those hard choices.
You are presently stuck between a rock and a hard place and the only one who can get you out of that place is YOU. My belief and also my experience is that you will need to 1. get professional help to assist you, 2. set unbreakable boundaries around your son(s) behaviors, 3. likely force your son to leave both your home and your mother's home as long as he continues on this path, 4. stay the course, no matter what bad choices your son(s) make, 5. allow your son(s) to experience the natural consequences of their behavior and actions and DO NOT STEP IN TO SAVE THEM.
You are likely reading that and thinking you could never do that to your children. And, of course, you always have a choice. However, what I do know is that as long as you allow this behavior, you will live with it, it will disrupt your life in ways you cannot imagine, you will become angry, resentful, depleted, filled with dread and walk on eggshells all the time. Your life will be taken over by the negative behaviors of children and substance abuse. There are predictable results and you are probably living them right now.
Some major hospitals and HMO's offer codependency programs for the parents/families. You might research those too. You can evict your 19 year old son and if that is the course you take, research what the rules are in your state because some states require legal action to do that even if it's your child. You can give your son a list of homeless shelters in another town other then the one you and your husband live in and insist he go there when you return home to your husband. You can get a restraining order if that is appropriate. Whatever road you choose, you are the only one in this situation who can make the changes. Your husband has drawn his line in the sand. You are the one who hasn't and you will have to do that if you want your life and your husband and your home back.
I'm sorry you are going through this, it is a huge struggle, I know. But you have the power to change it and you will have to be very strong and get help to do it. You should never put up with abusive behavior from ANYONE. As long as you do, that is where you will live. Your choice. I hope you make it today. Go get help and don't put up with this any longer. This is not your fault. You did not create this. You cannot change your sons, you can only take care of yourself. I wish you peace..................