my wife was not happy. who was right?

Definitly your fault. ..

Yeah, you dont do that sh*t! I would be mad and at my sister too.

Maybe that was a little overboard (both your wife being bugged by the behavior and you taking it upon yourself to remove your SILs shoes and rub her feet). Your SIL chose to wear the shoes she wore, so she knew the risks of them being uncomfortable. She could have kicked them off and gone barefoot for a bit.

because maybe you got too close to her. Just show that you still love your wife and re assure her.

No wonder why she was upset, what the hell rubbing her sister's feet?
Who cares if the sister was limping? It's her fault for wearing the high heels.
You're the one who rubbed her sister's feet, I'd say you're wrong in this one

Obviously your wife enjoys knowing he sister is in pain and you took that away from her .

You don't rub a woman's feet unless she's your girlfriend/wife. That's too intimate. She chose to wear high heels. I understand you want to be caring to her family but there is such a thing as going way too far. Picking her up may have pushed the line but she can damn well rub her own feet. Why ask the question if you don't want to hear the truth? You comment on every answer defending what you did. You were wrong, accept it. If you're going to defend what you did and continue to do it, don't be surprised if your wife finally leaves you and don't come here crying when she does. You have your answer. If you can't see what a serious boundary you breached, you're going to have severe issues in your marriage.

God bless.