Found out ex is seeing someone else. Can’t stop blaming myself

First off, dating for me is rare. Dating someone I’m actually into is even rarer. I was dating someone I was really into for about 5/6 weeks (i recognise it’s not long). But I was having these ED issues and we never actually had sex. Did other things but never sex. I went away on holiday for two weeks and when I came back she broke things off. I saw her last week on a night out (we have mutual friends) and she told me the reason was because she met someone else whilst I was away.
She tells me it’s nothing to do with me or the sex, but they’re just more of a match.
I can’t help feeling inadequate, incredibly jealous and I hate myself because I think had we been able to actually have sex, we would have had more of a connection that maybe would have deterred her from seeing other people.
We were never exclusive so I’m not angry at her for it, but it’s left me feeling incredibly shit and jealous. Dating is so rare for me (I’m 29) because I’m incredibly picky and for once it felt like I had found someone that I could have had something meaningful with, for the first time in like 7 years.

I’m struggling to cope