How can I get him back and prove I'll change?

Long story short: I've been a crazy untrusting bitch to my boyfriend and he's very sick of it. he's always done everything to make me happy, he's put his heart on the line when I haven't, and he's told me before that he hates how I don't trust him. I've showed him that I don't trust him, that I'm crazy and overractive, several times.

He has always cared SO much. Just two weeks ago he was telling me how he loves me and needs me in his life. But he said he's tried everything and he doesn't believe me when I tell him I'll change. What do I do? I don't want to lose him at all, he's precious to me. I know he must still feel the same way because his feelings were very strong. We're meeting in a few days to talk in person but he's set on breaking up. How can I fix this?
How can I get him back and prove I'll change?
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