What's bent and is it fixable.

In the interest of full disclosure, this is actually my wife's truck. She got rear ended yesterday, and I"m trying to find out what's bent. She was tagged by a jeep, with the brakes locked so the truck absorbed all of it. The tow ball was installed ( I mean, why not?), and I think that the jeep actually hit the ball. The whole bumper is bent down about 30 deg, but there isn't even a mark on the gate, which closes perfectly. The bumper isn't buckled at all, beyond being bent down. I think that some solid part of the jeep, like a front crossmember, hit the ball.
I looked underneath, and the crossmember that the hitch socket is part of has been moved, but i it's bent it's not by much. That crossmember is bolted to the (i assume) frame rail on both sides a few inches back from the leaf spring attachment point. The crossmember mounting plates aren't visibly distorted,, and the bolts are all there. The frame rail, between the crossmember and the spring mount, is buckled on one side, and visibly bent on the other.

My question is obvious, now that I've gotten all the TMI out of the way.
No one is going to pull that rail straight, not with that crossmember right there.
Cutting and welding frames is frowned upon by state inspectors, especially with a suspension pickup point and a towing pickup point right there.
This is all on the insurance company, and I expect them to try to write off the truck if it's not a simple repair.
More TMI.

 

Your assessment is correct, that is a crumpled section of frame rail between the leaf spring hanger and the bumper mount. Including a picture from when I had my bed off to clean up my frame. You can see the bracket for the bumper and for the leaf hanger. You've got a decent bit of rust on that frame as well

 

Simple, depends on your skill set. It can be fixed. With the amount of rust I see, I'd be looking at the frame near the cats to determine whether or not you want to repair it. If there is holes in the frame up there you may need a kit to fix those sections and I don't remember who sells the kit.
If you're going the insurance rout, I believe your insurance will total it.