When is it classes as harrassment

[Guest]

Hi, I need some advice. Long story short, I fell out with agot blocked, shut out, whatever you want to call it. About 2 weeks later I called this person twice, I had sent 2 like messages, on social media and by text message to try to reconcile. To my surprise I got the extreme reply of 'one more message or call and I'll call the police'. This was back in early June. I naturally said nothing else and left it. Now roll on to August. I still feel angry about how coldly I was treated. I do not want to harass this person but I really would like to tell them what I think. These days though, I am genuinely worried. If I wrote a criticising message without being abusive, could it constitute harassment?