Depends on how much that door was worth, and what they charged him with. If they charged him with malicious mischief, and the door was valued under $500, its a misdemeanor, any more and it can be charged as a felony. But they could have charged him something else. Either case, if they arrested him its generally a violation of probation/parole for any number of reasons, though I've heard of cases where probation officers did not violate for certain arrests, they have a lot of discretion.
Hopefully he gets the misdemeanor and he won't have to worry about 3 strikes, which he really needs to consider seriously in his future actions, because depending on the nature of his past two strikes he could go to prison for life on the 3rd felony conviction, or at the very least be sentenced to the maximum punishment on the 3rd felony.
He could still end up going back to prison for this most recent offense though. He's already been violated once on this term of probation for drugs, and they might think he was on drugs when he kicked the door in. Hopefully he'll test clean if they decide to test him, because that won't be a good look to the court. This could also be charged as a crime of domestic violence, which is not good.
This isn't your fault. He broke a law, he's on parole, sounds like he has some anger issues and he needs to stop his anti-social behavior.

