Go for it
If you want to meet your paramor's wife, then by all means go. At the moment you are just a image in her mind that she is trying to cope with. By coming to see you you will (at the very least) show that you are willing to face her and give her the chance to address her feelings and concerns to you.
As far as your fears of her possibly leaving her husband, try not to let them overwhelm you. Its, easy to try and place blame on oneself for the pain in the lives of our loved ones, however this is a matter that is more specific to the relationship that he and his wife share. Should the worst occur and she leave the most you should dare accept blame for is loving him, and being wanting and willing to work the matter out with her. Some could very well argue that it IS your fault for stealing his affections. The problem is that the heart is something that has little to any direction in how and whom it chooses to love.
To deny our emotions and our nature to deny the fundamentals of who we are. And in denying it we inevitably set ourselves up for personal disapointment and pain in our lives.
Well, I am rambling. Good luck to you hun and best wishes. If she opens the door for you to come talk I am certain you will be ready and willing to go. Take care.
If there is no Heart, the mind will never matter.