Anal... Condom?

My boyfriend and I are considering trying anal for the first time. I know it hurts so we're going to get lube for sure. I'm wondering if he should wear a condom or not? I'm not worried about STDS. I know we're both faithful and clean. But I'm worried about if he cums and it some how accidentally gets into my v. I'm not on birth control and I know it's very unlikely but I'm worried it could happen.