Do not worry about the CFAT, as PMed put it, it's about how you think. If you're worried about your age, don't be. When I did my basic we had a 41 year old who passed without a problem. In battle school, the second part of your training for infantry, we had a 36yr old who wasn't in the greatest shape, but who had the perseverence to keep going, and he graduated. We're now both at 1 RCR in Petawawa.
The only thing you and your wife should be worried about is how your kids will handle both parents being away for an extended period of time. If they're old enough to understand what you're doing and why, then go for it. If not, that is something you need to consider carefully.
Don't think that I'm trying to discourage you, this is one of the greatest jobs in the world, but I'm not going to sugar coat the reality of the lifestyle that you're choosing either.
Best of luck, either way.