My CPAP saved my life. I don't think I would have had the strength to go through all of the pre surgery, surgery, and post surgery without it, never mind be as successful as I have been so far.
If you have sleep apnea, you are severely sleep deprived and are damaging all your organs, especially your brain with lack of oxygen absorption. Sleep apnea is serious business, and I am amazed at how many people just find the mask a nuisance. You are going to feel SO MUCH BETTER after even only a few days on the mask!
Yes it's uncomfortable...I jerry-rigged several homemade pads to wrap around the straps so it would be easier on my face and ears. Do whatever you can to make it work, promise yourself you'll give it a chance. Honestly the challenge of using the mask is NOTHING compared to the challenges you'll have post surgery.
Also, you will be under anesthetic during surgery; do you really want there to be questions about your pulmonary health? People with apnea have extra special attention paid to them by their anesthesiologists and have extra monitors throughout the hospital stay. You wouldn't want to be on IV pain meds, fall asleep and stop breathing for good!
Please give it a chance. A good nights sleep is a miracle.