I agree with Annies post. I would say in touch with her. since you got so close, and I completely understand where you're coming from. but for now I was just be her friend and talk to her. its always good to have a friend in your life. especially a female, because sometimes men just don't understand.
I'd stay in touch but just not put myself into any situation where I would be tempted to behave like anything other than a friend. This means no late-night talks, no alone time with a glass of wine, etc. If you want her in your life, it has to be like any other woman friend.
I understand the companionship that you may be yearning for from her, but I honestly think because it was romantic at one point, that it is no different than if it were a man you wanting to be around....
I was always taught to avoid the appearance of evil. Maybe if the time comes where you and your man aren't together, then consider it. But you also said she has a family as well, and you wouldn't want to be a homewrecker. I would hold off a bit. I understand you two were close and this will be difficult for you, but you may end up complicating things more.