I think i'm having a problem with love and feelings. HLP ME PLZ!?

Ok there's this guy that I've been talking to for about a month or a little more now. I'm starting to really like him. He just got out of a relationship about a year ago that he was in for 5 or 6 years, and he got screwed over so many times. And that's the same as for me, I just got out of a relationship that I was in for almost 5 years, and I was constantly being let down by him. So now of course I have a wall up and I'm not having an easy time with letting him in, and I like him, but I don't want to go through what I have again. So by not letting him in, I"ve made a mistake the other night, which he was mad about but he is ok now. He stayed at my house with my step-brother, and I went out and said I would be back and I never went back, until the next day. I'm not trying to make it hard on him, even though I probably did, I'm just afraid of getting close again. And my stepbrother and his gf which is the guy I'm talking to sister, is telling me that he is really into me and he's not someone that will screw me over and I know he's not. My heart is just scared. But I don't want to keep making him think I'm not gonna be into this thing we have so what would be the best way to tell him, that I do want this, and I do want to try, but only with out coming out and saying the exact words? PLLLZZ help me out. Thanks.