I strongly disagree with the posters who are saying "too soon." You and this woman have a loving bond. When she asked you to stay away, circumstances were different. If you send a card or letter----and please don't leave your address off, that would be dreadful (if you're worried about ex seeing your address, put it in the letter, not on the envelope) it does only good---it will be welcomed by her, I can almost guarantee that----and you can put in, amidst your thanks, assurance that if she still needs you to keep your distance, you respect that completely. She's a strong, loving , mature woman and can decide for herself if she wants to restart your relationship, but she may be reticent about getting in touch with you now----worried that you associate her with your miserable ex.
I think letting her know that you love her for herself, and are grateful, would be a wonderful, positive thing. And you are right----life is uncertain and short. I'd do it now.