Remus wished that they could just be playful about this. There were plenty of things he could brush off or look the other way about, and most definitely had for most of his life. But this was not one of them. The whole furry little problem thing was a big deal. Remus did not like to say it controlled his life but in a lot of ways, he did have to revolve things around it. If it was just about him, he might not have been so intent in doing what he did. But even when they were younger, when he found out what Sirius and the others had done in becoming Animagi for the sake of being around him during the full moon, he'd gotten upset. He was immensely touched and grateful, of course, but he'd been terrified that they'd get hurt even knowing that werewolves didn't tend to come after other animals. It'd taken him a while to really be fine with them coming out during the full to run with Moony and even after seeing that they never got hurt too much (just some rough housing from tumbles in the dirt) he still always feared the worst because that was just Remus.
Now they were in a situation where he was surrounded by dozens of people who had no idea what they were dealing with. By no means would he ever be so arrogant as to think he was stronger than any of them but right now with so many people sick and unable to really fend for themselves the way they normally would, it was a cause for concern. Sirius included. And he knew Sirius would still put himself at risk to be there. So he needed anyone able bodied who could help keep Moony contained or at least distracted during the night hours to do so because he wasn't going to risk Sirius getting hurt. And he didn't want anyone else being put at risk without knowing about it. That wasn't right. He had to do what he did, and he had to face the consequences of Sirius being angry with him over it.
"I know, love," he said. "I know, and I'm so sorry I hurt you. It kills me--" His voice cracked with emotion and he felt the corners of his eyes sting a bit. "I'm so sorry." His fingers passed gently along his scalp, rubbing in soft motions. "They have a right to know, and I have to be realistic. I can't pretend like it isn't a big deal, that the worst couldn't happen."