FB blocking question.

So I had my boyfriend blocked this girl on FB. This girl had me blocked on her FB before I even knew about her, (1 year ago) needless to say. Today I discovered that she had unblocked me. we saw her at a distant at the same local event this past weekend. she was very aware we were there.

I don't understand the whole blocking thing on FB, but I do know that once you blocked someone, you cannot see each other's FB page. But I accidentally discovered I was unblocked by her because all of a sudden I was able to see her past comments on my boyfriend's pictures on FB. and I was able to click on her name and go to her page. (( and immediately blocked her, and for once i felt like I had the upperhand.) In short I didn't know anything about her and he had shared intimate,and personal things about me to her. but we are working on the relationship and my trust issues, but we are doing great.))

So my question is...If he blocked her, wouldn't her comments be hidden? or gone? or am I able to see her comments because she unblocked me. I want to make sure I have an understanding of how this FB blocking works and not get mad at him thinking he unblocked her.