Very angry at ex

I admit it. I cheated on him but he has also cheated on his ex before me so is certainly not innocent.
We still have each other on Facebook and still kept photos of our time together despite splitting early last year and both getting new partners.
There is one photo where I am sort of in a joke 'headlock' one of my ex's friends said 'Should have left her there.' and my ex replied with a laughing emoji. Does anyone else think this is completely inappropriate? My friend reported it to Facebook but I think little will be done.
We have a child together.