Teacher trouble. Please help me!!! Try to read it all.?

Well I should say ex-teacher. I'll try to explain this the best way I can. I know it's not right for me to feel this way, but I adore my ex-teacher so much. I'm not saying it's love, because I'm not just another dumb teen looking to score with a mentor. I also would never express these feelings to my teacher because I would never dream of putting her career and life in jeopardy. Despite my wishes of not letting these emotions be known, she probably does know how I feel to some extent, though I wouldn't verify that to her. Anyways, here's my problem. Throughout this school year I've yearned just to visit her cl and try to have a friendly conversation. I always seem to have the confidence to go prior to the actual visit, but once the time comes I get scared and can't pull through. I need advice on getting prepared and staying that way, because I've chickened out now about 10 times and I feel like a coward. I've actually talked to her once this year, but it must have only lasted about 5 minutes and I blame myself for not extending that conversation longer. So how I can I develop confidence and keep it? And remember I only want to talk and be friendly, because I know I have no real chance with this woman.