I'm seriously so sorry

wish I could help somehow...
In regards to your son, wait a bit, give him some time... You may try to spare him from seeing his "father" as a woman but your ex may have told him all sorts of things that made his head a chaos... Try having a talk with her and a talk with your son as well(depending on how old he is) because it's not fair that she's potentially making him turn against you. But I think even her might need some healing time, it's still too soon for everyone... So when u do talk to her try to, instead of being confrontational, to hear her side of the story, ask her how she's feeling, she's probably feeling betrayed, lied to, and a good talk could certainly help... Maybe she just needs you to understand the chaos she was put in right now and you might need to better explain your feelings and needs ... She's not being the nicest and you could make it a battlefield, but it's not healthy for you both and for the son. A wholehearted talk can move mountains

As for your health, I'm super sorry this happened to you, recovering from surgeries isn't fun
You are a strong woman, take pride on that

challenges are only given to people who are able to get past them. You're only getting stronger.
Send you tons of hugs, hope you recover fast and it'll all become past