Can I get a third-class medical if I have sleep apnea?
The short answer to your question is yes, you can get a third-class medical with sleep apnea in some cases:


  If your OSA is treatable, you can maintain your airman medical
  certificate and continue to enjoy your aviation career.


Everything else in your question is very personal and specific, and the only way to get an answer for your individual case is to consult an AME, preferably one who's handled similar cases before.