I resent my boyfriend's mental health
That seems very specific. What is wrong with your boyfriend's mental health?
He never leaves me alone and he never knew his place in the world
I can understand why you feel awkward about this. It is not okay to shame someone's mental health issues. Maybe you should suggest having him talk to a counselor about it.
Do you know what he said to me?
I do not, which is probably best that you don't tell me if it is something private that a counselor might be the better choice to know what you and your boyfriend can do to fix your relationship. Mental issues are more common than you think, so I think sticking through with your boyfriend and knowing that you love him is the best thing you can do at the moment.