Remus understands the flinch, that it's not really at him. He doesn't take it personally, and while he does regret causing Sirius to react like that, he doesn't regret taking care of his injuries immediately.

He numbs his rib cage too at the mention, though the spell needs to be a bit milder to keep the organs working properly.

It hurts to see Sirius cry like this, like he hasn't since perhaps their second year of school. He can't help but keep his wand in hand, though, as much as he wants to stroke Sirius' hair, to offer as much comfort as possible. Whoever attacked could likely return, after all. He tries to make sense of Sirius' babbling, and it takes him a minute, because honestly, it's been a while since he's had cause to think of Sirius' brother, but he remembers the note and things start adding up.

"Are you-- talking about your brother? Regulus was here? And--" Her-- B-- He let out a rather choice expletive. "Thank Merlin you got out of that alive. I love you too, Padfoot, so much." He'd tell Sirius about the note later, when he was a little more coherent. Right now, keeping him talking was more about distraction, keeping him from going into shock.