Subaru Outback engine failure

I was driving on the highway in my 2008 Subaru
Outback with 98kmilez and turn off a exit, as soon
as I turn I hear a loud poping noise and get very
worried my tire popped, then shortly after it smells
like burning and I pull off the the gas station
immediately (500feet ) and my car sounds very
wobbly and odd, and the check engine light starts
going crazy . I had to call. Tow truck because my
car obviously should not be ran at that point.
About a week prior I got an oil change and they
wrote on my diagnosis sheet it “looked” like I was
leaking oil from the head gasket and didn’t even tell
me, I only noticed what it said when I got home and
scheduled for another appointment (headgasket
replacement) for roughly $2k, my appointment is in
4 days and now in appears the whole engine should
just be rebuilt .