Sounds like your in love but if she is married and have children then it is a really big issue.

Before going ahead with anything ask yourself, does she feel anything for you? Is her marriage a happy one?

If she doesn't feel anything for you then it is best to keep these feelings to yourself sins it would compromise your friendship. She might not react well to this but if she is open to this then you could talk to her about it

If not then it is best to love her in secret.

Sorry I cannot be of more help.