I used to suffer very badly from apnoea and reflux. My sleep and my breathing were all over the place.
Things I did to change the situation:
1. Reduced (or at least changed) the stress. Divorce isn't an option you'd want, i guess, but it sorted a few things out for me
2. Lost weight. Sorry, no two ways around it, but apnoea is linked to weight. OK, so I was still overweight, but the more I lost, the better it got. The better it got, the less tired I was. The less tired I was, the better I could manage it. The better I could manage it, the more I felt like doing something about losing weight.
3. Broke the cycle of being up in the night. Hard to do, but it is important that habit does not reinforce clinical need.