You melted the gasket. You should be able to take a puddy knife and wedge between the top and bottom of the egg and work your around to losen and open. Then of couse you will have to replace the gaskets.
Try this link, and I also reccomend upgrading to the nomex gasket:
Wonderful Family, UDS Redhead, Mini Homer Simpson WSM, Smokey Joe Gold, Old style Smokey Joe, CGA , Green performer, 22.5' OTS w/ roti ring, 22.5 Redhead, 18.5 Redhead, 18.5 Redhead, 22.5 Limey, 22.5 WSM, 22.5 OTS Fire pit convert, weber fireplace, 18" Discada, Fish Fryer, Clay Pig Grill, Belson Trailer BBQ