You need big time trigger warning for your post.

Working before being officially hired with the expectation of a back pay is never a good idea. Having said that there’s nothing wrong with helping people for free but you are upset he used you for free labor. Otherwise it’s fine to do things for free

I do understand that you were introduced too hjm and that he had a rough life. But it doesn’t mean you got to know him well enough to do all that. That’s what I am saying unless you are hired and engage in strictly professional sense, don’t get that close that fast to total strangers.

If you completed orientation, background check and finger prints, you should have some record of it. Receipt? Certificate?