I'm not surprised that your client "friends" sent an angry response. They expected you to continue teaching their children for little of nothing and continue to pick the child up. They really had it easy and you were the one losing out on this deal.

Sounds like you are getting your ducks in a row this morning and rounding up what is due you. Good for you. Set those boundaries and adhere to them.

Sit quietly, the answers will reveal themselves when you least expect them to.
The past is gone, the present is a gift and you need to focus on today, allow the future to reveal itself when it is ready.