PrettyPretty,
First, I would like to recommend that you ask for your post be moved be to
http://imvumafias.org/community/viewforum.php?f=187, if that's possible. While this forum you've posted under is indeed titled Basic Creator Help, I believe it was meant for posts requesting help and inquiries relating to the actual creation process. There's also a higher chance for you to receive a larger number of responses to this post if listed as a topic in the linked forum, for the target audience in that forum is far wider than here, which is more or less just creators helping creators.
Now, with that being said, I'm really sorry to hear about your predicament. If you truly believe that they've ripped your products in particular, I personally would recommend that you contact IMVU support with any and all proof and suspicions that you have. Considering that you've already accused the person, you haven't left yourself much choice in terms of options. I would attempt to get room urls with them in a room while wearing your product. May not exactly help but worth doing imo. I would also try to get product details and the like. As well as screenshots of your "signature" within the products, if you left any behind. Basically gather any and all possible information which may be useful in proving you've been stolen from. Organize it all, then submit your case to IMVU.
I respect that you don't wish to "rat" the other person out, but in this case you've already brought the trouble to your doorstep, which, if you think about it, is the point of not ratting in the first place. So I don't see that there isn't much to lose. In fact, you're likely to loose far more by not ratting, since it seems you're genuinely considering giving up an account that you've put significant money and time into. So I would just state my case with IMVU support and hope for the best. You've already knocked the arrow at this point, so see it through. I wish you all the best with this.
Regards,
Xacto