AK preflop near bubble with a big stack, lots of action

[LearnedfromTV]

Pokerroom 20K, 700 runners, pays 70, Hero is top 20 stack with about 110 left.

Blinds 400/800

Relevant stacks

MP1 Donkey 18000
CO Hero 25000 has A[img]/images/graemlins/diamond.gif[/img] K[img]/images/graemlins/heart.gif[/img]
Button Aggressive with short stack 8000
BB 20000

BB is solid, hasn't gotten out of line, saw him overplay AK postflop once, raising preflop about as often as a big stack should, so he's stealing some.

Donkey limps. Means nothing. I've raised his limp 2 out of the last three hands, once with an actual hand that went to showdown, the other time with a bluff that didn't.

Hero raises to 4000. Maybe a bit too much? Not really the question except for how it affects the subsequent action.

Button goes allin for 8K (this is any ace, most pairs, good kings. BB makes it 13000. Donkey calls.

9000 more to Hero with ~ 40000 in the pot. If I push, it's about a 66K pot and I'm getting about 3.5-1.

Hero is scared to death of BB and...

folds and keeps his 21K?

pushes and hopes he can get to the Red Zone?

calls?