Whenever I get hurt, I hurt my boyfriend on purpose (not physically, by words)

Our relationship is 6 years old and I kept doing that since yesterday and yesterday he told me he is sick of this situation and he doesn’t want it to be like this anymore cause he feels so upset when I hurt him just like that. And I am not proud of myself hurting him back whenever I get hurt.

Now I have to build his trust again, how do you think I could do that?

I know I have that power to promise and keep that promise till the day i die but I have to make him to be sure and I have no idea how to. Could you girls tell your opinions. How would you trust a person again?