I never told him I had an abortion

when I was 27 I got pregnant with him. I really didn’t want to keep it. It didn’t work out with my job at all and I’d make a really, really horrible mother. I know that all sounds really cold and heartless, but that’s how it is. I was afraid to tell him, because I feared he’d try to talk me out of it. I had the abortion when he was on a businesstrip, when he came back I managed to pretend nothing had happened. I felt so horrible. Not that I regretted the abortion, but I really missed having someone to talk to. I made a mistake by not telling him, but by the time I’d figured that out it seemed too late to change that.
Eventually things got better and now (2 yrs later) we’re about to get married. One part of me says I should tell him to be able to start our marriage without lies and secrets, but the other part says it would only cause more pain if I told him. He might hate me for it. I really don’t know what to do.