I suppose there are never any guarantees in love, only probabilities. It's a potentially dangerous game. I'm not surprised he was immature if he was dating younger. I had an abusive partner who was my age (we met at university) but then has been going for younger and younger over the years because women his age have cottoned on. With young men they are untested (the boyfriend the same age as you). By 30, it's much easier to know who they are. The boyfriend who was the same age as you, what is he up to now? Is he going for younger and younger? Is he still messy?Do I have regrets? Yes, but because of who he was as a person, not because of his age.
He could have been the same age as me and behaved in the same way (belittling me, being dishonest etc).
In fact, I had another boyfriend shortly before who was the same age as me and acted in a similar manner.
I actually think I would have benefitted from having had a boyfriend who was more mature than I was at the time and who would have protected me.
I think mature men go for mature women with shared life experiences. If an older man is going for a younger woman, one has to at least wonder why given they are less likely to have things in common than someone in their cohort. I'm 30 and my relationships have always been in my age group, my cultural group and with shared value systems. Similarity is the name of the game in my experience, not difference. It eliminates at least several components of the power differential.
Actually when I have these experiences, I wonder why I am attracted so many weirdos. It's some kind of trapped energy that recreates the same experiences over and over again until that energy packet is felt through and released.