3400 ft of climbing in only 37 miles is a very tough route, so congrats for doing that.

Hilly is tough, long is tough. But both on the same day is really, really tough! Most of your climbing was early, so that made that part even tougher.

It sounds like you did this alone; a solo century is tough, so maybe try one with an organized event or with a group of similar ability. For me, this would have been an all-day thing, so maybe also reconsider your pace.

Don't be too hard on yourself, you'll get there. You did a difficult ride and learned somethings. Cycling can be glorious but it can also be cruel. Someday, but not today, you'll have great memories of the day you pushed yourself to the edge.