I need suggestions on why I'm so mean. Whenever I am hurt, i lash out. I say the most cruelest things that come to mind. I push people further away. I tend to do this most often with those I care for the most.

Current situation- 6 months since my ex said he didn't love me anymore, 3 months since he has moved out. We work together, live on same street; getting over him has been difficult. I somehow allowed myself (drunk) to have sex with him recently. It made me feel disrespected and hurt. I felt the need to verbally attack him, why?

What can I do to stop this behavior in future relationships?