I Think We Need To Break Up

I've been with my guy for over 4 years now, been living together for almost 2 years. Now don't get me wrong, I love him and care for him a lot, but I think the best thing for us would be to break up. We live together, we have a dog together, I've literally been with him since I was 15 (I'm going to be 20) and we want different things in life and difted too far apart. I know he's not happy with our relationship anymore, he's told me that about a month ago and never spoke about It again, cause I was too scared. Do you guys have any advice on how I could talk to him about possibly breaking up? Since we live together and stuff, any advice on breaking up with someone you live with?