Wonderful honest & transparent post as always! Your title drew me in saying the opposite of fear is vulnerability. I always felt the opposite of fear is Love.

In searching for the opposite meanings of fear I can a fantastic blog that I feel shows the progression of transitioning from fear to the opposite. "The opposite of fear is safety.
Safe to be real
Safe to feel stressed out
Safe to be imperfect
Safe to admit marriage problems
Safe to not have all the answers
Safe to make parenting mistakes
Safe to not have it all together
Safe to admit failure, struggle, sin, addiction”

The opposite of fear is acceptance, which leads to curiosity, which leads to a sense of understanding, which leads to feelings of safety, trust, and finally, love."- https://clarity-first.com/what-is-the-opposite-of-fear/