Those fuel injectors are all one piece. You've damaged the injector itself :( . The good news is the injector will still function. The bad news is that the o-ring will not be constrained. That means that when you pull the injector back out it will stay in the intake. You can fish it out with a scratch awl or small screwdriver, but you run the risk of accidently pushing it into the intake. Or when you install the oring, it may get cocked and not seal. I speak from experience as I have done this very thing
. The injector went in and in my case sealed ok, but when I later pulled the injector out I saw that the o-ring had gotten cocked during installation. I would not be comfortable running it like this. I would recommend you to replace the two injectors. BTW the replacements I got did not have these 'caps'.