Was I really the one in the wrong?

This situation was the beginning of the end for me and my ex, and while it is in the past I still can't figure out if I was the one who was in the wrong or not. The relationship ended in a very bad way and I have taken over a year to work on myself but this particular argument still confuses me and I was hoping people could help me figure out what I should take away from it.

So when we began dating I made it clear that I was not interested in being with anyone who had a habit of taking illegal drugs, whether it was part of their lifestyle or something they just did around friends, it was not something I felt comfortable with because of my prior relationship. I explained that while my grandfather had been fighting cancer and was losing the battle I couldn't talk to my then boyfriend about it because everyone I would call him or meet with him he was still on a come down. I felt unsupported and as if the one person I could turn to outside of my family wasn't in any fit state to listen to how I was feeling and I felt very alone, when things ended I didn't want to ever feel that way again. I felt like this was a reasonable explanation as to why I felt that way and I made sure to tell him early on just before anything got too serious between us. He understood at the time and there didn't seem to be a problem between us.

Moving forward to about a year and a half later, my boyfriend admits randomly that 6 months prior during a visit home around Christmas that he had smoked weed at a party and didn't tell me because he thought I would leave him. I reassured him that him smoking weed (which in my eyes is one of the more harmless drugs to take although I don't smoke myself) wasn't a problem especially as it was at a time when I wasn't even around him, but I did have an issue that he felt the need to keep it from me for six months and that his argument was he didn't want me to leave him. He also said he disagrees with my standpoint on any drugs and I was over reacting and controlling him. To me this came as a shock as I never considered myself controlling, I had always trusted him and never had an issue of him being out without me or having his own life, I believe trust and spending time apart are important in relationships whereas keeping secrets for months are a red flag. This began to really get to me, I thought I was inadvertently controlling in my relationship and became quite worried I had toxic traits I was unaware of. During the end of our relationship I eventually found out that he had not just been smoking weed, but had in fact been taking much stronger drugs such as cocaine while he was on nights out and even doing this around our housemates and pressuring them to keep it from me.

This is all the relavent information I can think to include, the relationship ended in a very dark place and like I said I have been working on myself since but this situation still confuses me. Was I right to have such strong opinions on who I wanted to be with or am I too guarded on the situation? Any advice or insight would be appreciated and I'm sorry for this post being so long. Hope everyone is coping in this current world situation ❤️

(Editting typo)