Torque
You can be a grandma at 55-65 ask my Mom she became a grandma 6 months ago
. Hell you can be a younger grandma than that these days.
From what you have told us more about you and your situation I agree with everyone and like you said when things cool down go for it and just don't tell her about it. Remember to make some time for yourself too you don't need to be there all the time. Even though your a good person it sounds like and helps with alot of the family stuff.