In fact, when students say this, they are only half joking to talk to you. Nothing particularly interesting should happen between classmates. So students sometimes say that you are an unscrupulous person, and sometimes they are just teasing you. You may have really done something that he regrets very much, or something that makes him very sad.
Even if the landlord's classmates say that about you, you don't have to care too much. Tell him why you said that about me and what I did to make you feel sorry. Then you two communicate, you should know why he said that about you, but basically nothing is too malicious.
The friendship between classmates is sometimes pure and worth cherishing. Communicate with your classmates more and you will naturally understand what he said.