I don't want the relationship anymore

I had been with my boyfriend for 3 years

How do I break up with someone who lives with me but doesn't have anywhere to go...or I should say he does but doesn't want to stay with relatives for whatever reasons.

I feel like I'm suffocating when I'm in his presence and I just don't know how to go about it.

I don't want to hurt him but I know that I will. But I want to be happy.