I think your existing children need all your attention.
They've been subjected to an abusive father, now they have another man in their lives for only a year or so. So many upheavals.
The amount of attention a pregnancy and new baby will take away from them may not be wise.
You're about to hit peri menopause, which is probably where this is coming from. And hot flushes, night sweats, anxiety, palpitations, itching, weight gain, emotional roller coasters ... all the favourites 😏... will be a very trying clash with pregnancy, childbirth, sleepless nights, toddler tantrums etc etc.
You've only known him a year - it's a gigantic double whammy for a new relationship to deal with. Do you really know if he will step up and be there for it? For you?
Also - be careful with a man who does not live with his own young children. He either left them, or she got them away from him.