It's a PEX hose fitting...probably 1/4" piping and made by Watts, Seatech (and others). Don't know the size of the brass, threaded end, but it's a standard RV water inlet (ass'y). Try a Lowes, RV supply or a more dedicated plumbing store for a Watts PEX quick connect fitting and do away with the rubber seal. You'll just push on the fitting to the pipe and screw on the threaded end. You should be able to remove the entire water hose inlet for easier access/repair. Kinda looks in a bind, there are elbows that accomplish the same thing as your straight.
just an exampleElbow
