Think about the first time you had this thought

Who was there? What did they say to you.

This trauma really affected how you think about yourself and others. Grieving this loss is important. It doesn't matter how long it's been since it happened. If you didn't grieve the loss it can still be triggered repeatedly. After grieving, try imagining that they said or did things differently. Imagine them giving you a hug or good advice instead of harsh words or deeds.