Oh heck- I think you may have to call Sony on this one. I have a feeling the only way that card will come out is via disassembly of the PSP. I hope you are under warranty and still have the receipt, otherwise you will have to pay for the fix. If this is the case, your friend should have to pay you for it, seeing as he was the one to break it.
What i would like to know is why would he stick that in in the first place? Does he not know the PSP doesn't even use SD cards, just Pro Duo memory sticks (guess he does now, doesn't he)?