Well, you've spoken to your sponsor which is good. I suppose the thing to do now would be to figure out what is going on inside of you that makes this situation go from an 'eughh!' And then forget about it event, to one that you keep replaying (re-sending) and causing yourself to feel in pain about (a fairly typical resentment situation).
You have behaved sensibly. Talked it through without drama, and discussed it with your sponsor, so you can feel good about that. One of the tools I use for this kind of situations is prayer. The resentment prayer (repeat application until stain has gone) and the humility prayer to help me figure out just what I need to let go of or move past in order to get rid of my resentment or fear. As I read the lists through the things that are causing me problems usually jump out at me, either making me feel a little embarrassed or sometimes angry and defensive. I can see a few in there that I might be left with if I'd been in your situation the other evening. Anyway. Might be worth a shot....
RESENTMENT PRAYER
God, I have a resentment towards X that I want to be free of.
So I am asking you to give X everything I want for myself.
Help me feel compassion; understanding and love for X.
I pray that X will receive everything they need.
Thankyou for your help and strength with this resentment.
HUMILITY PRAYER
God. I pray for your helping in detaching from the desire of being:
admired,
loved,
praised,
favoured,
accepted,
consulted,
well known,
and honoured.
I pray for your help in detaching from the fear of being:
Criticised,
ridiculed,
humiliated,
falsely accused,
persecuted,
disbelieved,
despised,
and forgotten.
Please grant me the grace to desire that others may be :
Admired more than I,
praised when I am unnoticed,
chosen though I may be set aside,
preferred to me,
and increase in prominence though I remain hidden.
Although others will do what they want, I pray that you will use me for your will.
I pray that I will pause, and while I pause help me to remember to pray for guidance and grant me the humility to find willingness and discard willfulness.
AMEN.
Hope you find some serenity regarding this soon.
BB