Sorry for your loss we experienced that situation many decades ago.
Adoption may be something to consider. My son was told that he couldn't make a baby so they adopted our grandson as a baby...... he will be 18 next summer. In all that time he has been well loved by his parents and us. What happens a lot is that we forget he's adopted and will see some mannerism or it's something he says and one of us will say he's just like his Dad or Mom then we look at each other and laugh that once again we have forgotten he's adopted. There is no difference in how our family feels about him nor our two surprise surprise granddaughters who are 4 and 5.
Now on to your questions about what to do religious wise here's a way to handle this problem. Do not tell your wife your finished with being a JW. Love and cherish her and as part of your grieving process do reveal how upsetting it's been for you to learn that there appears to be a wide spread Pedophile problem in many of the congregations. This is not unique to the JW's but the problem has been exasperated by the Society.
Talk about the two witness rule......what abuser wants a witness to their acts. Treating sex abuse like a a sin instead of a crime. Not encouraging, up until recently, a parent to contact the authorities immediately. Not informing the congregation that they may have a pedophile in their midst even going out in Field Service.
Talk about the recent Royal Court in Australia investigation and how they found from the Branch records something like 1106 JW judicial committee investigations...... 400 Dfings and over a 50 year period not one notification to the police. Elders and a Branch member and one of the GB member were questioned under oath and were not very forthcoming.
That this has raised an issue for you as you can not and will not hide this problem in your KH if it arises. And above all until the Society takes strong measures to correct this issue you will probably have to step down.
See how she reacts to that as a first step.
She may be opened to understand things are not always right in the Society.
If she has reservations about shunning those who simply want to leave the JW or as a teenager were DF...... she may also be sensitive to forcing an 18 year to leave home when they are still facing problems (like drug use etc) and really need the support of family.
Since the loss of two children is the dominant issue in your lives.... at this point framing your need to get some space and look at things a little differently family wise may be an approach that will help your wife to start considering some other options.
My best wishes for both of you.
Gio