How do i say it?

So lately ive been really depressed. I have alot going on but i feel like its just getting worse and sometimes I think about suicide. At first it was like yeah ill say it but never actually do it but i find myself thinking about it more and more and everytime I run it i have less and less reasons why I shouldnt. Anyway I want to talk to my boyfriend about it "we live together too" I just dont know how. I dont want him to worry about me and I dont know how the convo would go or how he would take it. Should I even tell him? I feel like I wont do and its only a thought.