I went to change my fuel filter and it is the original filter and is just destroyed and rusted on along with the fitting, so now it is completely trashed. i am going to have to cut the line to get everything off unfortunately. so ill just have a bare line coming out with no flare end.

My question is what is the best way to get something back on there?

i thought of flaring out the line where i cut it, but its tight and might not be able to get the tools down there to do it.

You can use a compression fitting to attach a new flared section of line with a bend to match up to where the filter is. Make sure the line section is clean bare metal and paint over the fitting and lines with bed liner or undercoating to protect it from corroding and rust. Since it's low pressure it's fine to use a compression fitting.

What.kind of compression fitting?

The compressing kind for cars.