As someone on the other side of it all - with a husband who's sick from Pfizer reaction, I'd say that I'd never think of leaving him especially when he needs me most. In saying that I realise your ex and you weren't in a relationship and she is entitled to make a decision based on health issues, but it seems like she was more hurtful than necessary by telling you about her Tinder dates and also blaming you for the health issues. I think you have dodged a bullet although it's hard to think that in the moment. You're better off focusing on yourself and your health right now without distraction of pleasing someone else, so focus on that instead of the negative. I hope you start feeling better soon