I would get the surgery done immediately. Well to be honest, I would have had it done when she was first bleeding and the grey area showed on xray.
Yes, there is a small risk of loosing her in surgery, but not doing surgery she is definitely going to die. That tumour could bleed out at any time. You are lucky in that the tumour has given you warning and time to get it removed. We aren't always that lucky. I've had a couple whose first indication of anything wrong was when they were bleeding out and it was too late to do anything but say goodbye.
Nobody can tell you what to do. This is your decision and a decision you are going to have to live with.
* * * Nancy * * *
Retired from breeding
Rescue contact for both the Hedgehog Welfare Society and the IHA
Rescued over 70 (and counting) hedgehogs needing a new home