Help with inheritance

I never thought I'd have a reason to post here. I wish I could trade my reason for posting for my loved one back but here I am.

I have a few questions and I completely understand if this post gets taken down. Not really sure where to go for help with this and I'm too broke to afford to ask financial institutions. I hope I don't make myself sound too ignorant.

I stand to inherit between thirty eight and sixty eight thousand dollars in a few months and I'm trying to figure out what to do in either case. The amount depends on how much the house sells for and if my two sisters expect me to pay for one of their car payments due to the car being financed for them by the deceased (I have no idea how to handle this situation either).

I am just over thirty thousand in debt and have a 275k mortgage at I believe a 6.85% interest rate. I do not have a car payment but my car is attempting to die on me daily.

I am 35 years old and just started contributing to a 401k April of last year. After my monthly bills I will have about 600 to spare monthly (I have had less than 100 bucks to my name monthly after bills for most of my life) not including gas and food.

I have never had an opportunity like this (this feels wrong to say when it comes in the form that it does..) and I am extremely scared of screwing this up.

I will reply to any questions openly. I'm just trying to figure out what not to do and if it also happens to make my life better at the same time I could definitely live with that.