Do you ever reach a moment in your life when you realise who your friends are/arn't?

I seem to have lost a few friends lately. All for different reasons. One told me off like a child when I was rude enough to cancel our plans to go to my grandparent's funeral. Another told me to "stop being selfish then" when I told him I had had a misscarriage, and another wouldn't stop groping me. I overheard the girls at work calling me stupid names like "lesbian" and "wierdo" which hurt but I let them go too. I spoke to my mum about it and she has had the same problems with people all her life exactly the same as mine. Could it be my personality? I am no pushover let me asure you but I am not brash/rude at all, my family all say I am a smiley happy person/fun to be around but I find it hard to believe when the people around me don't seem to take to me very well. Even romantic relationships often end up with me getting abused and a few times got threatening texts from exes. (I did leave them btw) any suggestions?