I've felt (and still do) much the same I believe. Beyond sadness, the force behind it is shame. Feeling like a failure for having to "Throw in the towel". Giving up, in just one more way, on sucking it up and "Being a man". We had a long lifetime of being told and practicing that technique for life.
It envelopes me with each major step and even minor ones. That eternal struggle of being true to yourself vs being what others want of yourself. Made all the more overwhelming the more in touch with yourself you get and the more importance you put on at least trying to finally do something for you. Yet in the background is that constant whine of "I'm feeling a lot better now. I CAN beat this."
In telling your daughters, for them it was a major change to their world view of you if they really had no idea about your GD. I'm sure it wasn't easy telling your wife of 20 years as it wasn't for me telling mine of 30 who also knew from about day 1 of my GD. But, at least, she kind of sort of knew there might be a ticking time bomb. Still, there is fallout. Now, you sit, wait, wonder about the fallout from your daughters. The days, weeks, to months of anticipation from initial response to reality setting in.