Is what I did illegal?

I had a roommate for 3 months, he lied about having a job, said he lost his ID and couldn't cash his checks. I caught him lying, and kicked him out because he owes me $3,000. I kept all of his stuff as collateral. I said when he pays me back, I'd give him his belongings back. He then went to jail for violating his probation, so I sold some of his clothes to a used clothing store, and now he's telling me that's a felony...? Is it a felony?