Travelling via the US for an ex overstayed visa traveller?

Back in Dec 2003 when I was younger and stupider, I left the US to go back to the UK (I am a UK citz), after overstaying my visa by 3 years (during my time in the US I married a US girl & then got divorced after it all fell apart after a month) - I went to the US in 2000. I totally understand this was my choice, my fault, and I broke the rules, and I can accept why the US wouldnt want me to travel back in to their country, but I was wondering if I could still fly to other countries via the US, on the transit visa & if so what would be required.

I wasnt deported, I just turned up at the airport and got a flight home - no one from customs said anything and I wasnt detained. I did go down to the local immigration office, and they said just go to the airport and catch a flight - they didnt seem that interested (bigger fish to fry I suppose).

I have heard that I may have to prove that I actually left the US, and they might not have it on record, but to be honest I have no idea where to begin.

Any help would be gratefully received.