What is it he says you are overreacting to?
Is the scenario: he does something hurtful, you are (Naturally) hurt, you tell him his behaviour is hurtful?
is THAT when he tells you you are overreaching?
Because that would be an abusive relationship.
Abusers like to tell their victims they have no right to be mad when they, the abuser, do something shitty. This allows them to continue to do that shitty thing, and, makes the victim doubt their own sanity, which comes in handy when they want to treat the victim like shit in any other way too.
And, for clarity, you should never need to explain basic human empathy to a grown adult. If you do, chances are you are in an abusive relationship.
Some people might go “ oh what about autism” but look, whilst SOME autistic people may struggle with empathy, they still aren’t going to do OBVIOUSLY hurtful things to people. Because even if they don’t feel what you feel, they know right from wrong and they aren’t cunts. And if it is a nuanced reason for the hurt, then once you explain why you are hurt to them ONCE, they are usually mortified that they have hurt you like that and do not repeat the behaviour.
There is absolutely no excuse for a partner not caring about hurting you, even if they have valid reasons why empathy can be a struggle sometimes.