So sorry to hear about your disappointment.
I went 13 years without seeing my grandmother because my husband did not want to spend his vacation in Kansas. We have 2 daughters and it dawned on me that I was never going to see her again. And I couldn't blame him, I had to take the plunge and just go. My grandmother was 88 years old, we live in Southern California, my daughters were 5 & 8 and I said I am going. It was cheaper for me to drive than to fly, so we did the 3 day drive each way. The girls were great, I think we hit every Dairy Queen from Chula Vista CA to Burlington KS but we had a great time. It was a shock to the rest of my family and friends - but life is what we make it. Right?
We did it again the following year and that time my husband decided to come along.
The following year I flew out by myself or her 90th birthday. The end of the year she suffered a stroke and unable to return to her home. So I was glad my daughters got to meet their great grandmother and see where I spent the first years of my life.
Not sure how old your boys are, but even if you had to go by yourself, I would vote that you go and have a good time. So you don't stay as long, you never know who will be there next year.
Try not to stress, I always say when things don't go as planned it will make for a good story later on. Maybe we can't laugh right now, but we will later.