Pete,
I'm sorry for all of your recent losses......that of your beloved step mother and the opportunity to mourn her loss at the 'official' services, as well as the control to force your body into doing what you need it to when you need it to.
Please let go of the guilt. The fact that no one in the family called to check on you and make sure you were okay when you missed the services tells me that you probably wont get a satisfactory response when you apologize for not being able to get there. Some people just don't 'get it'
We do, my friend.....and I'm sure Nana understands too