One more thought - Have no idea what fare basis you are on, but is worth asking UA what the refund will be if you cancel (you have that option) and asking DL what the routing you want will cost and whether there is anything they can do for you in light of circumstances. Depending on what your refund will be and what DL is willing to sell you, maybe there's not that much difference. But, be very specific here becs. RT fares are often not simple twice the OW.