Trying to be strong

I know and I realize I need to be next to my wife, supporting her every step of the way, and I am happy to do that. Unfortunately, I don't know where the line is to say "I love you and want to help you, but I need some time to myself." I feel selfish if I say something like that, and worry that I'm not giving my wife the help that she desperately needs. I suggested last night that I wanted to spend some "guy" time to just leave the house and do something for myself for a little bit. I'm sure this is just a part of my grieving process, but I can't help but feel guilty.