It's a common and valid question, and this is a great place to ask. I didn't really have that worry because I was my hubby's first lover and wanted him to have the chance to experience sex with another woman. I found that what turned me on wasn't so much seeing him with her, but hearing her noises and knowing he was pleasing her. After all, I know how good what he's doing feels to me.
If you already have good communication with your husband, you're on the right track. It is SO important to be able to discuss anything you're thinking and/or feeling with your partner. If thoughts of having sex with others (or in front of others, or watching others) turns you on, then by all means consider exploring the lifestyle a bit further. Talk about what things excite you and what doesn't. Talk about how you think you'll feel about having sex with others and seeing each other do the same. Talk about what guidelines or rules you think you should have to keep each of you and your marriage safe. Peruse this site, read any forums that interest you, and talk some more.
When/if you feel your ready, you can try going to a club or a meet and greet . . . Just see what's out there, and observe. Or you could jump in feet first (like Mr. Sweet and I did)!
Either way, just proceed at whatever pace you're both comfortable, and have FUN.
=)