I like to use the following formula for decisions like this: Which will I regret more?

1) Will I regret having found this friend that I have such fond memories of and not reaching out to let her know that she made an impact on my life?

2) Or will I regret having found this friend, taking a chance, and sending the email.

Intuitively I feel that if she had a similar experience she would love to hear from you. And if you misread the relationship, then, like you said, she will likely ignore the correspondence.

I would go ahead and reach out, but make sure it is very "you" focused. "I have thought about you over the years and wanted to let you know that your friendship was an important part of my journey." Provide contact info if she would like to respond and leave it to fate to determine the rest.

Good luck and let us know what happens if you do reach out!