1999 Honda Civic ex

call overheated a couple of times and
pushed water out of a small hole on
the very top of the radiator. but after
filling the radiator again and making
sure the upper flow is full so I could
just stop doing it. what about a
thermostat and my friend was going to
put it in that night but I'll stop at the
grocery store and had the AC on when
suddenly I smelled a breeze and poof,
stain was everywhere but not like the
typical radiator hose burst, it left as
fast as it came which was weird but
anyway I got home my friend put the
thermostat in but called me over to
see something. He said you have to
have a new radiator because that's
what happened when all that steam
came out and pointed to the entire top
of the radiator looked as though
someone had took a knife and sliced
the top right off and Sat it back down.
You can clearly see The crack I have a
radiator on the way however my
question is what caused this to
happen? With the thermostat sticking
cause it to run this bad hot, had
enough to cracked the top off the
radiator? And I also wanna replace
this radiator Do I need to get new
hoses and replace them as well? Is
the thermostat the only thing that
could cost us? I just want to fix my car
so bad