I feel bad even after I speak up. I sound horrible too when I try be confronting and often when I do I regret it afterwards. I'm learning to not getting worked up by keeping silent which actually seems to be working better for me.
When in doubt, it's a good idea to sleep on it. Especially if you're upset. Also, you might explain what's happening to someone far removed from the situation. An old friend, a sibling, or maybe even a parent. Someone who can give you more objective feedback and advice. The last thing you want to do is let your emotions make matters worse.