You seemed to hit the nail on the head when you said if you'd given her space, you wouldn't be in this predicament. So if that's what she needs, go ahead and give it to her. It's not going to make things worse. You can still fix your own individual problems.
Giving her space may give her time to work through her confusion. She may be hell bent on the divorce and that won't change whether you give her space or pressure her, so you might as well just give her distance. She may come around or she may not. Best to prepare for the worst.
Just because she filed for divorce doesn't mean it's what she wants. I can't speak for her, but I filed because I was fed up. I didn't want a divorce, but I wasn't willing to continue on in the marriage that I was in and my husband wasn't willing to compromise on the issues. I don't think anyone WANTS to get divorced.
I would move the stuff to the garage only if it's truly going to be easier or best for you. I wouldn't do it if it's just an act of emotion to try to be spiteful. Will she be upset if you do that? Is the argument that will cause worth it to not have her friends in the house? If not, I'd just suck it up and let them in the house.
Don't assume they're more than friends. You'll eat yourself up inside over something that may not even be happening. Even if they are more than friends, you and she have a broken relationship right now and divorce will mean that you are both free to see/date other people. It's hurtful and ugly to think about, but divorce isn't pretty.
You don't really have a choice but to concede and part ways. She doesn't really need your cooperation if she's intent on leaving. You'll only piss her off even more if you stand in her way. You don't have to be okay with it, but she's going to do what she wants anyway. Ultimately you need to do what's best for yourself right now.
