What To Do Next?

I met a girl (20 - I'm nearly a decade older) a few months ago through work (she was temp-staff). Instantly attracted through her appearance. Got talking on her last week, got subtle hints she liked me, became more intrigued by her. Her employment finished, but we stayed in touch through social-media. We spoke on there for a couple of days, but felt strong guilt when she hinted at meeting up (I had a long-term girlfriend at the time, and I told her this after the meeting-up suggestion). Was shocked at myself because I had been unfaithful in the past, but didn't want to hurt the new girl/also wanted to change my ways. Anyways, we stopped talking completely after we had cleared up that revelation.

Months later, my relationship ended. Got talking to the new girl again through social-media. Told her I was single, exchanged numbers and messaged very regularly for 2-weeks, where she even agreed to go on a date with me. The date consisted of the cinema and drinks. We were both nervous beforehand, but those nerves had long gone when we met, no awkward silences and continued conversations. We were out all night, shared numerous kisses, and I had a really good date/night. Whilst walking to catch a taxi, her mate we had bumped into started interrogating her about us, asking what she seen in me - to which she replied she could see herself in a relationship with me. Woke up the next day to a message from her saying she had a good night and that she really likes me.

All looking very positive. Until...

In the following days her messages weren't as regular, and her replies were shorter. Concerned, I pulled her up on the matter a few days later. She said she does like me a lot, but doesn't feel that she is the right fit for me / the timing isn't right for her when she originally thought it was (a lot of stuff going on in her life, but she won't elaborate on what) / thinks I deserve somebody better than her. Also some random remark was made about how she, "Never wanted me to put all my eggs in her basket". How many eggs does she want me to have in different baskets?!

Game over.

She's a very attractive young woman, but appears to have a lot of self-doubt in herself. Even when we first ever got talking on social-media all those months ago, she kept telling me she isn't a very nice person and that I am too nice for her. She even brought it up in conversation when we sat down for our first drink, minutes after meeting up, saying she hopes I never find out how nice that she isn't.

A big part of me does think I've been friend-zoned, but another part of me thinks her ex maybe involved (on her walk to meet me, she walked by him after not seeing him for many months and she was visibly shaken by it) which may well coincide with her "timing" situation, and she did drunkenly mention why it never worked out with him (he was 13-years older and they both wanted different things, and she assumed things might be the same for us as well). She also enquired into my previous relationship too (in time we became more of a friendship than a relationship, and the new girl said she didn't want the same thing happening to us). She was drunk at the time, but not the sort of stuff you bring up on a first date.

I'm probably just clutching at straws in regards to her ex, but she has left things open to more questions than answers after stating I didn't understand what she was meaning - but then not actually telling me what she means when I asked her! I told her that I am willing to wait until her head is in the right place / things weren't as complicated for her, because I do feel she is worth the wait. That last comment was just shot down as, "Really sweet, but not true".

Apologies for the lengthy message. Thank you and well done for reading it all. Maturity (or lack of) is perhaps the biggest stumbling block? Opinions/what to do next about the matter are more than welcome...