I released my pet mouse into the wild
Why did you release your pet mouse outside?
Because it was making my life a miserable. I think it will benefit from dealing with the challenges of nature.
While it seems like all mice are the same, any animal born and bred in captivity and treated as a pet will have a hard time surviving in the wild. Releasing it outside is harmful to the mouse as it doesn't know how to gather its own food.
A mousie who doesn't know how to survive is a mousie that isn't alive for long.
You shouldn't adopt a pet if you're not willing to take care of it throughout its lifespan. It will almost certainly suffer trying to adopt to conditions it's never known. How would you feel if you were an adopted child and your new parents decided a few years later you were too much trouble for them so they left you in some dark alley in the middle of the night?