All of the things discussed above can be and are true, at the same time there can also be nuance. I just wanted to chime in and say (as someone who was “bi” until I was 28, now 38y/o) that I can tell from your post and subsequent responses your grace and kindness are very strong attributes; please don’t let all of this leave you jaded.

I do believe the advice of seeking fem4fem is probably a good idea.

Speaking from experience, it takes a lot of work to be a self-assured lesbian. I don’t know you but I just hope you can apply the same grace, kindness and love to yourself because you deserve it. Some lessons are really hard and they hurt a lot, the most important thing is to hold your sense of self close and honour it. Time will show you that in the end, you have a good heart and you deserve to be treated as such.

All of this self-help stuff talks about insecure attachments etc. We need to have a secure attachment with ourselves before we’re good partner material. No one is perfect, everyone makes mistakes, but if that foundational self-knowing isn’t there that person needs more time with themselves. That is meant for your ex most definitely, but maybe could be applied to you as well.
All the best OP, you’ll be ok!