Mood swings with my boyfriend

My boyfriend is really sensitive, and gets hurt easily. He also worries a lot, and I have a major mood swing problem. The other day I was freaking out because I hung up on him by accident, and I didn't realize it, so I called him back and was crying. Long story short, he got pretty annoyed with how many times I apologized to him. I really hate hurting his feelings, but I can't really control what comes out of my mouth when I'm having mood swings. Any suggestions?