okie girl, everybody said everything I would have said. I want to underscore just one or two things at most.
You have told your husband that YOU ARE NOT PUTTING MONEY ON HIS BOOKS. I think I read that.
Even if you were only to put $5 a month on his books, that would make this a lie to your husband. You are afraid to tell him the truth because he might leave you. That little lie makes you vulnerable all of the time. Because in your heart you know.
You know I worked in prisons over a 20 year period. The money is used for gambling, for extortion, for drugs. That is the in and out of it. There are many, many inmates, the majority, even who are considered indigent. To be indigent has its advantages because the prison is forced to provide you with the basics, for clothes, toiletries, leather boots, etc. (I am in another state, mind you.) And there are jobs. There are usually jobs. In some prisons the pay is good. In some places, there are few jobs or the pay is low, but here is the thing:
The men who do not receive money or packages develop businesses. It's called "a hustle." It can be something as simple as collecting a certain type of garbage from the ground like candy wrappers, that some inmates use to make useful things or crafts. Prisoners are the premier recyclers. Every single thing is reused or made to suit a purpose you would never dream of. Other inmates become artists, and draw and paint beautiful custom greeting cards. Other inmates become jailhouse lawyers: they help others with their legal paperwork.
Every penny you send to him takes away your son's incentive to get busy and to provide for himself, and reinforces seeing life in terms of dollars and cents, instead of what is intrinsically valuable, like love and work. You have no way of knowing that one dime of that money is used for his enjoyment or his well-being.
Given your husband's position, and your assurance to him, I would stop.
I spoke longer than I intended. My perspective does not come from the place of making him suffer or feel the effects of prison life. I think when we lose our integrity in our relationships, we lose our self-respect. You are caught between two people. Neither one is happy with you. Be happy with yourself. The right thing Is to honor yourself.