I’ve called mine a crackhead too. It’s hard not to view the person like that when that’s what they are doing all the time.
Could you write to him in prison? He needs to face up how his behaviour affects you and the child you share.
Unfortunately, the people I know who are crack users and end up in prison tend to use when they get out. I think it’s because it goes with a lifestyle and like you said, their friendships or acquaintances tend to also be users stuck in the same cycle. When they get out it’s hard to readjust to life outside prison and if they don’t have a job then there’s loads of free time doing nothing, which can cause an issue.