I had been planning to ask my ex to marry me tonight.
Why did you back out?
I've learnt a lot about her.
I get why you would back out if you learned something that surprised you. It wouldn't be right to propose now if this is something that you find troublesome.
Do you understand what I am saying?
I understand you said she was your ex and you nixed your plans to propose, as you learned something new. I think there is probably a reason why she was your ex in the first place and it seems like it's time to move on.