I don't deserve the person I'm dating

For the past three months I (26F) have been dating someone (26M) who's way too good for me.

It's not like he treats me as a 'princess', but he checks in on me regularly and makes sure I'm comfortable at all times. I know this is something that should be normal, but I'm afraid I'm going to use it for my own benefit. I can be quite toxic and manipulative, thanks to previous relationships, but I absolutely don't want to be that person. It's hard to get this out of my system, even with all the help and tips from therapy. I'm working on this daily and it's way better than half a year ago, but I feel like I have a long way to go and I don't want to treat him badly.

He's some sort of sunshine I haven't seen in a long time, and I'm honest when I say he makes me so incredibly happy. I haven't been this happy since I was a kid, or maybe since forever as I can't remember much from my childhood. He's the reason I live my life so much more positive, not only because he's in it, but also because I live way healthier than before, thanks to him.

It feels so good between us, but I'm afraid I'm going to blow it one way or another.

Update for the ones who are interested:

I spoke to him about my negative traits and asked him to tell me when he notices something odd about my behaviour. He responded by asking for examples, and even though I hate to talk about my exes, I'm glad he showed interest and wants to help me. I didn't say anything about me being afraid, but I'm still planning to do so when the time is right.

Thanks for all your kind responses x