Unfortunately you have been in a 'toxic relationship'. It happens to the best of us.
When we are in a toxic relationship, one side is more into the relationship, they are wanting to feel loved every minute of the day, constant reassuring, unreal jealously, thinking that there is no one better out there, fear of breaking up, thinking of dying so as not to have to live without them, even going as far as a cry for help.
There are people who bring the toxic side out in us. As much as we think we need and want to be in this relationship it is better for everyone to end things. It's usually the side that's not into the relationship as much who ends things.
Having the toxic side brought out in us, doesn't mean you are toxic inside, it just means that you need to be with someone who brings out the happy side in us.
This will pass how you're feeling, you will get stronger, you won't always feel like this. It is better to leave the relationship now, try to be strong, tell him he's right,you are not meant to be together, you don't need that side brought out in you. Get whatever help you feel you need, sometimes we can heal just being out of the relationship.