My mother had the surgery done when I was a teenager (she had the ligation after I was born). They were able to successfully reverse the ligation, but she later lost one fallopian tube due to an ectopic pregnancy. They are now the proud parents of a 10 year old girl(who happens to have Down's Syndrome) but it was a long road for them. I won't go into the details but, in my own experience: just take a good look at the risks and decide for yourself if you would be okay with all possible outcomes. Maybe yes, maybe no. Your perogative as a mother. I wish you all the best.
****Post Script****
I gave this some thought over the afternoon and feel perhaps I did you an injustice. The fact is that my mother (who was 39 when she had the reversal) had several miscarriages, had a little boy who died at birth, and lost another little girl when she was about 6 months pregnant. In addition, my little sister's Down's went undetected and was a major surprise at her birth. My mother is an incredibly strong woman, yet she was completely torn up by the whole experience. It altered my life as a mother as well. So, I don't know how old you are (I'm guessing you're a touch older, as you've been married so long) but I just wanted you to tell you the truth. It's a harsh reality, but there it is. I wish you and your family the best of luck in making this difficult decision.