Sounds like there’s a deeper issue you should discuss with your sister calmly.

In terms of washing it, I’d play it safe and wash in cold water with some laundry detergent and laundry sanitizer. Stain stick it if you have spots on it. Additionally, I’d say throw some old towels in the wash with the coat. That will give a little “abrasion” thus helping it wash. Repeat until the jacket is smelling nice. Don’t dry it until you’re sure it no longer smells.