Regret texting my ex

I was casually dating a girl in college when I was 21. Messy ending with me getting blocked everywhere. she fueled that however by keeping in contact through blocks and also adding me back/unblocking me during that dynamic. taught my brain a block was negotiable. we ended up with a very healthy closure email exchange, forgiving each other for all the mistakes we made and wishing each other the best. I should have left it at that. I was happy. But for god knows what reason, after a year of silence, I decide to DM her on instagram the only platform I was not blocked on (but also also not following her, it was a message request), but this time I get a message from her boyfriend accusing me for making her feel uncomfortable and in a rather aggressive and condescending way commands me by saying, “you’re going to stop reaching out to her and move on“ . what should I make of this? did I deserve that/ is this even normal? I just apologized for her discomfort wished them the best and walked away from that toxic dynamic. I dont need that drama in my life. I regret contacting her, honestly changed my entire perspective of her. I’ve learnt that when you have closure it’s best to just let it be, instead of trying to reopen it after a year, you never know what’s on the other side and honestly feels like a setback.