Nice?

I'm a nice person. I just am. I don't say that as a pat on the back kind of comment. I just mean that I veer more toward the nice side than the mean side of things. No one would ever be scared of me, lol. You could call this passive or meek or doormat and you'd probably get my meaning better. It's what's easier for me, to play nice. I find it difficult to speak up when I should or not be taken advantage of. I've become painfully aware of this and have been feeling sick of it.
So when a situation arose recently that I had to say something rather confrontational, I took a deep breath and just plunged into it. I didn't say much, just enough I thought. When I was met with defensiveness I simply answered that with the same straightforwardness and then considered the matter closed. I walked off without really thinking another thing of it.
Apparently I was the only one who felt calm in that situation. I later learned that this person had gone around bad-mouthing me to several people who then of course came and told me about it. This made me feel angry at first. I thought, wow, if this person thinks I was hateful, then they're gonna have trouble adjusting to what is in store for them that's for sure! I felt bitter about all the confrontations and harshness I've encountered and how easy I was on this person when it was my turn to do the confronting. After that came the guilt. This person does not know me, at all. They don't know that I veer on the side of nice on most occasions. They don't know that I'm the last person to get mad about little things and definitely the last to confront someone about it.
I contemplated how I  could rectify the situation. Should I go to them and apologize? Did I do anything wrong? What would I be apologizing for? Should I ask them why they felt I was hateful? Wouldn't that just be another confrontation that apparently this person doesn't like? I've finally decided that I can't control how other people react to things. I know I was not in fact, harsh or hateful and there's really nothing I can do to convince them of this. I will just let this go and be more soft when I speak to them next time. I will remember that this person is very sensitive to criticism.
Once again, I will not sweat the small stuff. I will let this person continue to avoid me and whisper behind my back and just leave it to God.. where it, and everything else.. belongs.