What recourse do I have? Will going after him for contempt be a defense against the HOA collecting?

I'm very sorry to hear about your condition. Sadly you are probably on the hook unless your agreement says otherwise. I would suggest suing your ex.

Do I have a case to sue them for the damages?

Yes of course you have a case. If it can't be resolved a demand letter would start the process.

Am I good?

Great question. Sounds like an oral agreement. Superseding event. I would try to work something out since it is your friend.

How long after the so called violation can she still file a claim?

Well the rule is two years to file.

What happens to the proceeds of a building listed as joint tenants after one member dies?

The surviving owner gets the entire property.

Can he be charged?

Yes it is a crime in the state of Pa

Can I go back and apologize and pay for the items? What do I do now?

This is a first. I would have a lawyer make the communication on your behalf to protect your penal interests.

How do I move to reconsider an adverse decision, and what are the time limits?

That sounds like a problem. If you have no lawyer which is unwise you should still attend court regardless

What is the worst case scenario and the best case scenario. I am a wreck and need some clue what lies ahead for my son.

If a misdemeanor up to 5 years in prison. You should talk to lawyer to review his options.

You may want to consider your own expert to fight the court expert.