I am trying to pinpoint exactly which part of this I find the most irritating.
The fact that he considers your weight to be something that requires forgiveness from him - as if you have personally wronged him through gaining any weight whatsoever. OP -Your body is your own. It's not his property. This is a disgusting way to talk about a partner - like they are some kind of possession.
Then again, I'm also massively annoyed at the fact that he is clearly a fucking moron. Scientifically, objectively and even plain socially - YOU ARE NOT EVEN REMOTELY OVERWEIGHT. You are smack in the middle of your weight range.
To be honest, your previous weight sounds incredibly unhealthy.
Why on earth would you stay with someone who felt entitled to make such idiotic, unnecessary and cruel comments about your body?
Even if you were massively overweight, there are ways of talking about this to your partner without deliberately trying to make them feel like shit.
I suggest you send him two links:
One to a BMI chart with your height and weight mapped onto it, and then another with a google map plotted from your house to his parent's house. Where all his things will be waiting for him.