You didn't win that one it was a draw. Australia finished higher than SA in the Super Six table, and that was determined by the obscurity of net run-rate
Do not flatter yourself. Cronje winning the toss on a Edgebaston pitch knowing to cause troubles for the team batting second. A South African team that lost to Zimbabwe and who's top and lower oder did not fire for the entire tournament almost. Same team who Australia beat by 5 wickets in the same tournament. The wicket of Cronje who he missed by a mile but was given out? South Africa were a 196 after 48 overs. At one stage it was 58 runs of 36 balls needed. You are telling me that everyone thought you would lose the match at that stage? We had no right to win that game and basically did not deserve it. Like against Sri Lanka, Like against Pakistan, Like Against England we were saved or got put close by Lance Klusener. Australia choked just as much as South Africa as they went through on technicality not a win. Klusener clubbed 31 of 16 balls to get us back in that game. In the end the better team went thru and won the world cup.
A choke happens if a team from an unseemingly un-losable (excuse the made up word) ends up losing as a result of the pressure (see NZ v SA at 2011 CWC). Not where a team that is equal to its opponent (or possibly inferior in talent) loses after never being in a commanding position. Australia were in command of that match till he clubbed that 2 fours 3 balls and no wickets in the bank. Klusener couldn't run singles with Donald on the otherside it was 2 or 4. It did not happen.
But how about Australia needing 117 to win in their last innings with a 23 year old called Hansie Cronje as captain in his first match. 5 runs to win Glen McGrath hit it straight back to De Villiers. Can we call that choke?
How about Australia scoring a world record 434 then went on to lose the game? Can we call that a choke.
Getting 332 against NZ couldn't defend it shall we call it a choke?
I can name many other matches as one can almost call any match in ODI cricket as a choke as 1 man can make the difference. We had to break world records in tests and ODI's to beat Australia. That is how good the Australian side were that you have to go to great lengths to topple them. They were always better than SA we just played above ourselves to stay competitive with them until the end.
As for the question did Sri Lanka choke? No. Sri Lanka was carried in the final by Jaywerdena who were they're best impact player.
11 things you don't know about World T20 2012