I got really accustomed to walking on eggshells, trying to be my alcoholic ex's caretaker, thinking it was my job to manage his reactions to life's curveballs. When we lived together and he was drinking, this was mainly a safety issue. But it got so ingrained into my mentality that I continued the behavior even after our relationship ended.
It was the reason I avoided immediately filing for child support, avoided the legal custody issue for so long and neglected lots of other responsibilities. I was afraid of his reaction. I was still scared of making him mad, of provoking a negative reaction.
A lot of this was behavior that was ingrained in me from childhood. I was made to feel responsible for other people's emotions, especially the negative ones. I still struggle with it today. My first instinct is always to appease, smooth over, fix or otherwise try to manage other people's bad moods and negative emotional reactions. I have to force myself not to do it.
You're doing the right thing for your son. As others have mentioned, your husband is an adult and responsible for his own stuff, however much he may have tried to hand you the burden of his emotions in the past. I know that it feels "wrong" to take an action that might provoke a negative emotional reaction in another person, but that feeling isn't a fact. Your focus is where it needs to be right now. You are protecting your child. That is ALWAYS the right action. Your husband is an adult. If he's upset about this, then it's a good time for him to talk to his sponsor or a counselor and see how he might use this as an opportunity to strengthen his own recovery tools.