Nothing good would come of it and it wouldn't produce any results that you might hope that it would.
Your ex's character will eventually be discerned by your sons as well as your true character. It may take some time but you will likely have a chance to have the relationship that you want.
Also, because big changes will be occurring with the Organization/JW religion over the next few decades, while things may look bleak now, the chances are that they won't grow up to be like their father in the way you fear due to these external factors.
Finally, most children desire to hold their parents in the best light. It is never a good thing to either bad-mouth the other parent (even when true) or to use the child, even in a passive way, as an act of aggression or in a manipulative way. Your bringing up the marital rape or any kind of negative facts about your ex, will be seen by your sons as an attempt to manipulate them into loving you and not loving him, and they will resent that. Additionally, making them uncomfortable over your relationship with your ex will only reinforce a desire not to be around you which is certainly not what you want.
You want to make spending every minute of time with you a joy and something that they crave so if you do have the opportunity or whatever contact you do have always keep that in mind and do everything in your power to create that feeling.
So just continue to express love and let things develop.
Regarding the legal situation, keep checking around to see what resources may be available to you. The main thing is that you can go back to court to have the custody reevaluated if there is a signficant change in either your or his circumstances, so if your health does improve or something occurs to make it possible for you to have more custody, you may be able to get the present order adjusted.
good luck,
Eduardo