Need advice

I’ve been dating this guy for 7 years now. We have our own apartment and a dog together. Lately things aren’t going the greatest and we have been fighting constantly. He says he wants to leave me and even threatens to do so when he gets enough money saved up for himself. Whenever he says that I get so upset that I just want to end it but I always seem to hold back because of our dog. It’s so stupid but I don’t know what to do. I know I deserve better than this but I don’t know how to make this better