im sorry to hear of the trouble you are having.. i recently joined this site.. and everyone here is very supportive. I just got sleeved 4 days ago and if it weren't for the people here i don't know what i would do.. everyone helps everyone out. answering questions. getting support, and just having an ear if its needed.. i wish you good luck in your journey because it sounds like you have done the research and you have mentally prepared for the journey. Now you just need some tlc from those closest to you.
My family was doing the same thing. they really didn't want me to get this surgery. and just as you i have been an athlete all my life even in college but after 4 knee surgeries its very hard to stay active. I have to admit its not easy trying to get support from family when all they can see is the negative, but they will come around. You just need to make sure that you are doing this for yourself and not for anyone else. If they dont like well then that kind of their problem and if they truely love you no matter what they will be on your side.
good luck to you and i will keep you in my prayers!