I'm terrified of confrontation - anyone else with me?

I've always been pretty afraid of confrontation. At this point in my life, though, as an adult, I feel like it's only gotten worse - or at least I'm more insecure about it because I feel like I need to have more confidence/conviction in my decisions/opinions at this age. I'm so terrified to speak up that I rarely express my opinion even when I have a strong one. Even with my family...if one of my siblings does something that I find ridiculous/hurtful/upsetting, I don't confront them for fear of hurting / alienating them. Basically, I can't stand being on bad terms with people I'm close to. Does anyone else feel this way? and/or does anyone have advice on how to approach confrontation/arguments when they make you extremely uncomfortable?