I installed a lock called the "door guardian" last week that works well and was easy to install as long as you have a small gap between the door and the jam as most doors do.

I found some at Ace Hardware. It's a plastic shell that covers the door nob. Meant for toddlers, but it worked fine. I liked them because I could quickly snap them on when the situation escalated, and there were no extra keys involved.

Thank you so much! I'm so sorry that you had to resort to this too 🙃