I'm pissed off at my boyfriend for using his ex's name on accident when speaking to me.
Why does calling you by his ex's name bother you?
That was his first love. I don't want to be connected with the memories of her.
It sounds like a simple mistake. It's unhealthy to get mad because they made a mistake. If you continue to be angered by this, he might leave you.
It's still wrong for him to mistake me for his ex. If he doesn't apologize later I am going to leave him.
By staying angry at someone it can poison a relationship over time. if you have an issue just be upfront with them and talk it over, otherwise it won't solve itself and you will continue to be upset.