Not strong enough

I work with high school kids. I do love my school and usually my students but some days make it hard to remember the good. Today I let a student make me feel more then worthless
I allowed (am allowing) her to make me feel like I am causing harm. I let her intimidate me. I left the building in tears. Although my coworker is supportive and tells me how much good I do, i feel like those words don’t penetrate the surface. I thought I was feeling better. I had a plan for v tomorrow. Instead I find myself awake after midnight, crying, and searching for an anonymous outlet.