My sister crashed my car once - sent my insurance through the roof for the next few years. I'm still annoyed about it!! Good luck with your brother. Best to be 100% honest and hope he is in a good mood.
It kinda hard to tell. Need to know if the alignment is off, the radiator, engine parts.
9000$ (Alignment, bumper, interior bumper, repair frame, radiator, minor engine)
Just tell him and get it over with, only a trained mechanic can tell you the real figures.
I will say Interior damage is likely, such as interior bumper and radiator.
And alignment are so easy to screw up.
Not to mention the insurances gonna fly through the roof cause he lend it and it crashed.
If it makes you feel better.
Insurance will help you through it.
And it usally over quickly.