I felt I accepted it, but I wanted to now why he did that?
It was important for me to know his motivation for saying that.
It went downhill the more he talked.
I am not obligated to accept an apology that may not be genuine.
I don't think that continuing to discuss the offense is a part of accepting the apology. At least, not AFTER accepting it.
Next time, I might suggest you say, "I'm still too hurt and too angry to accept your apology. I need to ask you to think about apologizing later, after I've gotten over this. Then I'll be able to explain why I am so hurt."One thing I've learned by being a parent: asking someone "why" they did something is just not a good move. They don't know why. Or if they do know why, they don't want to admit it. So don't even go there.
It puts them on the spot, and frankly it's the equivalent of scolding.
Stick w/ "I" statements. Like: "That really shocked and upset me." "That made me tremendously self-conscious, right in the middle of my party." "I felt angry that you couldn't just let me alone, it felt to me like you were picking at my appearance right where everybody else could here." "That comment didn't feel concerned, to me--it just felt critical." "I find it hard to enjoy the party, now that you've pointed out how funny I look."
It's OK to sound a little bit mad, I think. But don't get into HIS motivation--that's really just scolding (which you'd admit if you really looked at it), and nobody reacts well to being scolded. Grownups least of all.
Even though it's a bit parental, it would be better to say something like this: "In the future, please do not comment on my appearance. There's nothing you or I can do about it right at that moment, it's not like my shirt could be tucked in or something. And if you're genuinely concerned for my health, please speak to me *in private,* not in the middle of party when everyone can hear it."