I'm very sorry to hear what you're going through - it must be terribly confusing and painful.
When you say he is "recently" dealing with his addiction, what does that mean in terms of time frame? Sadly, once the addiction takes over, it becomes the primary obsession and need for the addict - at the expense of everything else, as you've seen. It doesn't mean they don't want to be clean, just that the addiction has become so powerful that they are willing to do anything to get more. Often they do not get sober until they are forced to by using all available resources they can get their hands on, and often ending up on the street - so you must protect yourself, your child, and your assets - or he could well drag you all down. As long as you are there for him he will probably continue to use, and
he really needs to be in a rehab. Ultimatums often do nothing but allow the addict to continue using. It might change when you are actually gone.
You can get more specific advice at this link below - one of the sub-forums that deals with this sort of thing (where a family member or partner is addicted). Please protect yourself.
https://www.soberrecovery.com/forums...tance-abusers/
And.. please read the Sticky note at the top of that page called "What addicts do".