The challenge to say what I'm not sure should be said

Lately I find myself not knowing exactly how to find the words to say what it is I truly feel. The downside to this is that as a result, it makes me shut down all together...where all my words just leave, and instead of trying to conjure up the courage to say what's true, and what's real, I just walk silently away; as if there were no burning thought I needed to share and get off my chest. Silence is golden, but not always the best remedy for situations needing immediate attention. Some things I've held on to for years and I'm just either ready to put it all out on the table now...go for broke, or just let it go all together. Usually, I choose the latter. But I'd have to deal with the thought of what life would have been like if I had held on a little bit longer; if I had revealed what was concealed. One of my downfalls is that I expect people to know already what it is I hope I won't have to say. Some things are obvious, and some require a more intentive look...a little bit more work. I don't want to see a friendship destroyed on account of me not being able to open my mouth and say thus, thus, and thus; but at the same time, I don't want to overstep my bounds and I fear that most people are challenging me; most situations are challenging me to do that very thing. That's very uncomfortable.