How do I discuss my fetishes with wife when she is very sexually passive and insecure?

Lots of reassurance! Starting small. If she is insecure - is there anything you (or the two of you) can do to help her feel more secure? Is there anything she does like or want that helps her feel less passive. Is her passivity a result of her insecurities - maybe exploring together would help? Lots of good information - there are good books and websites that will help. That would be a start. 

It might be easier to start bringing up fetishes then - with an understanding that we are all wired differently when it comes to sex, and some people are more kink or fetish oriented. It could be a vulnerable conversation, but one worth having. Find some good educational websites that talk about your fetish without judgement.

Start with something you think she'll be most ok with, something she can easily learn about and gain some confidence. See her reaction.  Reassure her. Explain to her what it means to you and what it would give you. Risk being vulnerable. Connect with her, truly. Be very patient. Set her up for success. No pressure, no judgment. See if you could present it in a way of exploration, discovery, creativity, play. 

A good counsellor will help with that conversation and exploration.