Umm.. Probably more information would really help us give better suggestions. What do you mean you "say the wrong things?" What are the wrong things? Hurtful things? Or you get angry and say things you do not mean? Or do you mean you'll say something... say something that's a touchy subject and he goes off, therfore making you feel like you've said "wrong things." In my opinion, it's important to say how you feel. Of course you shouldn't let your feelings control you or get to the point to where you obsess over every feeling in your gut. I've done that and it was a really nasty feeling to keep having. It took both me and my partner being patient, easy on each other, understanding, etc. before I finally got my head in the right place. I am sensitive. Lol.
So it would help so much to know an example at least of what you mean by "the wrong things." What happens when "it gets bad." Does he automatically yell? If so, you may want to consider thinking about whether or not the relationship is right for you. Is it to the point of him verbally abusing you? It's not good to scream and yell with your spouse because when that happens, all control is lost. I'm by no means telling you that yelling or raising your voice, or even that being angry is wrong. It's normal, and by all means, if you're so angry, go ahead and yell. But it's really good to try and maintain calm. It's hard though, I know. I sometimes get crazy. Lol.
If you truly are having a problem, and it is one sided--meaning your problem and not something HE is contributing to at all--then you could try thinking before you speak. It's not so hard. It only sounds hard. Just remind yourself throughout the day to say something nice and that will help you not say negative things. Again, I have no clue what types of things you're talking about so I could be giving you horrible advice. Maybe come back and elaborate a little? I'd be happy to let you know how I keep from ripping my Lovie's head off. Lol. No, I'm not that bad, but I'd definitely be able to tell you more about how to deal with it if I knew more of what you meant. I've had to practice being kind and not saying things before. I never say "I hate you" or anything. We actually never say anything to really belittle the other. I have said things like "Where'd you get that ugly-ass thing?" When I was angry and he proudly showed me a bracelet that a friend gave him. It was rude and I had sat at home with anger building up over something I worried too much about, and I ended up being hateful when he had no clue why. Those things, I know all about! Lol.