Hi Bluey.
I would just like to echo everybody's sentiments: I'm really glad Mushroom is home! (what a cute name!)
I agree that it would be smart to keep her indoors now. There are obviously aggressive cats in you area and I'd hate for her to get hurt again.
My friend's cat, Pebbles always went out, but once she disappeared for a few weeks. When she came back, she was injured and had lost a lot of weight. Everyone was worried sick. Now she is strictly an indoor cat. In the beginning, she was not very happy about it, but she got used to it. Now she never tries to get out.
Please understand that I'm not telling you this to scare you...It's just that I know you're worried...we all want to keep our beloved pets as safe as possible.