I can't decide whether to break off my friendship or try to hold on for reasons of logic.?

I have a friend of over 20 years who has stood by me and supported me, but I have also suffered a lot of ridicule and disrespect. Lately there was an incident that really made me want to put an end to the friendship. But, my logical side tells me I maybe should not remove a source of support, while my heart tells me I should empower my self-esteem by confronting the person and making them aware that I won't take the abuse any more. I am very torn on this issue.