Of course your concerns are valid!
If I had been put in that situation, even if it was my sister or boyfriend - who is my primary care taker, I would most likely chose to decline the invitation. I'm trying to recover well enough to be able to work full time (or more) again and it takes all my effort to do so. I can, personally, not handle any more significant setbacks at this point in my recovery and attending just one graduation ceremony would put me in a world of hurt for several days. I'm working about 20 hours a week right now, with limited responsibilities, and that's difficult enough for me to handle with the cognitive and energy impairments that I'm dealing with.
Only you can figure out whether it's worth it to you to try to go.