Please don't worry. You will be fine. I also broke my 40 day fast on watermelon, but juice, no chunks at first so I probably had a higher concentration of sugars than you. I was a little more gentle but I still felt I'd overdone it the first day.
It was OK, my digestive system was tender and I felt I'd had enough Sugar so I made a batch of vegetable stock. Just small amounts of kale, broccoli, carrots, green beans, peas, a very small amount of bell pepper, a few alfalfa sprouts in a big pan and boiled it for 30 mins. Then I just sipped the water. Delish! So refreshing. A welcome break from melon.
My stomach is waking up slowly now and I am giving myself a full week of no solids. Next week I'll try a few pieces of steamed veg (keeping the water to drink too) and raw, easily digestible fruits and veg in very small amounts.
Again, please don't worry. You'll be fine.Be gentle on yourself and take it nice and slow. You haven't done anything that will cause irrepable damage.