I'm also amazed that the puller broke before stripping out the crank arm's internal threads. Most of the requests for help we get here concern a crank arm that has had the threads stripped out but the puller remains intact.

That said, and since the OP plans to replace both the crank and bb, I think his best bet is to use the Dremel and a cut-off wheel to cut through the crank arm in two or more places at the bottom bracket eye and then it should just slip off. Use fiber reinforced cut-off wheels as these are far more durable and won't shatter if they are twisted slightly.