I couldn't be happier for you and your dinner party guests, or more proud of you and your progress. Now, why are you feeling down? Maybe just because it is part of the roller coaster. I really hope you won't try to read more into than that, or over analyze it.
Maybe it is something of an over correction. Consider that rule "for every action there is a reaction". You had some really up beat "highs" with the party and friends. Maybe you expected to feel some "highs" when you spoke to the kids and tried to improve their R with their dad, and it didn't happen. Coming back down to normal might have left you feeling like you just had a big emotional dip in the roller coaster. Please don't focus on that.
Take some time to read your recent posts and highlight the things that stand out as positives. Make plans to repeat the positives. Focus on the positives. Even if it means that you work your student to death
I remember when you began trying to test the waters of GAL. You had scheduling difficulties with friends. Local bars weren't open when you were free to go out. Restaurants were not convenient or you couldn't arrange company. You couldn't leave the kids at home. So many things stood in your way. And work was not good.
Look how you have changed these things. Look how you have changed. You are still on the roller coaster but you have taken more control of the ride. Please continue to do this, and give yourself the gift of time and patience.