Tbh the posters saying everyone comes accross as 15 are being harsh. I don't think op sounds immature at all tbh. No more so than anyone else who is out of one abusive relationship and into the fire with another and so, maybe not thinking as clearly as would be ideal.
But I'd second doing the freedom program op and reading up on how to spot abuse and types of abusers and how it can begin. As it can present in various ways. Keep reading up throughout your life.
Sometimes we make the mistake of thinking 'on but he's not like the last ex' because either the abuse presents differently.
Or sometimes they love bomb us in the beginning and make us feel seen and loved after out past abuse and - we really, really needed that. So when their mask starts to drop, we find it hard to accept that they are more of the same kind of jerk our ex was. Because it also feels like admitting that all those nice things they said and did that made us feel worthwhile and lovable again, were a lie.
And that's what they rely on to keep you trapped, constantly chasing their 'nice' behaviour and trying to avoid this...dark cloud that seems to come over them at certain time or regarding certain things. As pp said, now it's about your ex, but in time there will be more and more things like how men look at you or how you dress or your friends not liking him or whatever...and you'll find yourself in this continual cycle of tip toeing around him out of fear thar you will make him mad/throw strops/guilt trip you etc...
The red flags are already showing. Not even a yellow flag. A big red neon flashing one. So, beware.