Roommates boyfriend is using our laundry machine to do his laundry.?

My boyfriend and I purchased a fixer upper that has an in-law suite I the basement. At first we we just going to connect it to our home to make it more spacious for us but then realized that we could defidently use the extra money to pay off our debt from having to fix up the home, which was in worse condition than we originally thought.

At this time a friend from my childhood was looking to move into the city and we offered the in-law suite for cheaper than we could have rented it out for and included all the ultilites so she didn’t have to worry about this much due this month and that much next. All was going well until we noticed the washing machines were contasntly running when her boyfriend was over. And yesterday we figured out why. We saw him haul a large garbage bag into her house and figured he was doing his laundry. So we set up a camera in our laundry room and caught him red handed pouring his bag of dirty clothes into our machines. Now what upset me even more than being used was that when I woke up and saw the pictures and heard the machines being used, my friend wasn’t even home. She was at work and he was over doing his laundry. Am I over reacting? Or is this something that is not right/okay? I do not want to cause problems but both my boyfriend and I do not feel okay about this and like we are being used.

** the laundry machines are ours and are not in her area of the home. We said she could use them to be nice but didn’t say anyone else can use them. **