1993 Caprice Classic major brake problem

I've had nothing but trouble with my Caprice's brakes for the last year or so.

Last year, around Jan/Feb, our temperatures dropped down to about -30F, and I had a weird issue where my brakes literally froze. I couldn't push them at all.
I let the car sit for a few minutes, and started slowly pumping the brakes, and eventually got them freed up.

A few months later, the brake line going to the rear popped. I eventually got it replaced. Then a few months later, the front brakes started scraping and squealing, and so I replaced the front pads and calipers about two weeks ago.

Now, the other day I was slowing down to make a turn, and my brakes completely went out. When they did, I heard a pop from up by the engine. I pulled over, lifted the hood, and there was brake fluid covering my hood, abs unit, and a small amount on the engine.

Does anyone have an idea what would cause this, what part would need replacing, and roughly how much labor it would require?

I'm strongly considering trying to get this fixed and simply selling/trading this car, as I've had nothing but problem after problem with the brakes, in addition to a few other minor things.

20+ year old brake lines aren't new. The annual "global warming" episodes and all its ice and snow cause the magic pixie salt trucks to appear and make your lines go away from the outside even faster. After a couple decades of that, lines are going to fail - It's just the reality of it. If it makes you feel any better, the 2005-ish Honda and Toyota families had complete subframes rusting away, not just brake and fuel lines.

If you like brakes (and who doesn't?) simply locate the leaks and repair them.

Then FLUSH THE SYSTEM completely and install new brake fluid. Old fluid absorbs and collects moisture. That will freeze, just like yours did. It will also accelerate brake line rusting from the inside. You car didn't get built with 20 year old, wet, contaminated, compressible, and low-boiling-point brake fluid, and it doesn't deserve it now. The $15 for a quart of new fluid is an investment.

Of course, if you had been following recommended service procedure, you would have already changed the brake fluid three times (every five years) and wouldn't have those problems.

The beauty of your '93 is that it likely uses the Bosch 2U ABS unit, and no special procedures are necessary to bleed all the fluid through it. It may be helpful to cycle the ignition several times during the flush to make sure the ABS unit cycles and purges, but bleeding air through usually isn't a problem. Just bleed at each wheel just as you would on a vehicle without ABS.