A very very tough situation sanchy. I feel for you.
If you want to have any chance of convincing your wife then take your time - but definitely resign. Be firm but go slow. From this moment onwards do not mention doubts until you have been announced as no longer serving. Just tell her you love her but have a lot of thinking and bible study to do.
Field attempts to "shepherd" with "thank you so much but not now; it's all a bit stessful - perhaps after the baby is born" - repeat ad infinitum and when the baby is born put it off further.
Emphasise how you need to resign so as to look after your family. Say you were too young when appointed and that you must focus on you and your wife's spirituality (which is not the same as WT rules and dogma) first before you can be any use to others.
Do not get drawn out about your doubts. Rehearse what you will say. Plan what "they" might say. Stick to the script. "I need to concentrate on my family/ it is too stressing to serve at the same time."
Between now until AFTER you have been announced as "off" spend your time being the best husband you can be. Be attentive to your wife and the new baby. Keep saying you will not serve until your baby is born and you have settled down. This can take at least a year or two after the baby has been born.
Do fun things. Keep family study non-controversial. Make the theme Acts 20 v 35 about giving. NOT MONEY but time and energy to the elderly and downtrodden. Let's make a cake for Auntie Doris. Let's go for a walk and look at the creation. Pick the flowers.
Obviously if a blood issue or a crisis hits then you may have to take the gloves off but until then "box clever". This will buy you 12 months of thinking time to plan and build up relationships outside the borg.
Your wife is scared and emotional and pregnant. Reassure her of your love.
You are scared too. Don't be afraid to admit that to yourself. I repeat. Take your time there is no rush. Armageddy isn't coming.
Best of luck. You will get much good advice on here.
Your main goal (I recommend) is that you an your immediate family remain intact and strong for each other. All else is secondary.