To not be ready for the OW to meet my kids despite her being pregnant with their step sibling

Why do you think it would be bad for your DC? Understandably you are raw, but what's best for the children?

There's nothing you can do I'm afraid. He's obviously a complete shit.

There isn't a right time, and it's an absolute shitshow, but the facts are this woman is already pregnant, so I think sooner rather than later is better.

Nothing you can do, if it's what their dad wants. It's probably better that your DS has chance to get used to the new partner being around before the baby comes anyway. Otherwise it will go from being just his dad, to his dad and a whole other family, rather than being staged so he already has am established pattern of seeing his dad with her there and then the baby comes along.

It's terrible your ex has done this. He obviously isn't putting his kids first and you aren't wrong to feel the way you do about this all happening so quickly.

There just really isn't much you can do. The only way you'd be able to stop him foing what he wants on his time with the kids is to stop him seeing them himself. Which obviously is not an option, because he would easily gain access if he took it to court. Potentially 50/50.

Just to add step siblings and half siblings are completely different. The baby will be your children's half sibling, a step sibling doesn't share either parent, and half siblings share one parent.

You are not unreasonable to be unhappy with the situation but assuming the child's father has parental responsibility as well then he can introduce the child to whomever he pleases, as can you.

Probably best to let him get used to the step-sibling before the baby is born and then they can share that together.

This change is happening whether you like it or not. The timing will always be awful for your seven year old.

how involved is the dad? That would be my guide. I have DC with autism who would struggle massively and I would protect them from this shit show if needed. Really would depend for me how much the dad is involved. or did he just dump the lot of you?

It's gonna happen either way isn't it? You can really stop it from happening if dad insists.

I'd do all you can to lessen the impact on your DC by easing the transition. 2 new siblings is going to be difficult. Even for a neurotypical child. Let them question things, be as honest as possible (I know how much this must sting, regardless). Make sure YOU have someone you can talk to about your feelings on this. Your ex is a massive shit for doing this. Obviously not really thinking about the DC he already has but it's done now. It's about damage control.

Gosh, OP. What a horrible situation.. No advice, but I'm sorry.

I think biology has taken control here. I rather feel you have to strap yourself in for a rocky year and get the introduction proposed, expected and done so the baby can be proposed, expected and done. He deserves to meet his brother as soon as possible after the birth.

But, perhaps discuss with the senco or his teacher about how they think he will take the life change.

And perhaps make your house routines rock solid so he knows exactly what he is coming home to.

No advice OP but I'm sorry your STBXH is such a colossal shit.

I think I'd be inclined to be as low key about it all as possible around your 7 year old, safe in the knowledge that eventually both your children will be able to work out for themselves exactly why their parents split up.

Does your DS like story boards?
My own DC does better with picture boards to prepare for change he's not use to. You could collect pictures of things babies might need to get him invested in knowing change is about to occur? (Or better yet his dad could)

A seven year old is not going to understand the awful timing,and if he is having contact with his father then there will be baby talk and stuff going on and someone is bound to say something to him. I think it will be better if it comes from you. Try to put a positive spin on it about how exciting it will be for him to have two baby siblings and how he is going to be such a special big brother to both of them. I know it is an awful task, but it’s about his feelings and expectations, not about yours atm.

I am only sorry you are having to deal with the shit your ex has piled up on your doorstep.

Yanbu but as one of your children’s parents is a shit one, you might not have much choice.

Awful. I’d be fighting the urge to take the kids and disappear. But I’m not advising that, really. It’s just how I would feel.

Yanbu. What a horrible man. However as there's a baby on the way the sooner the better so your 7 year old has more time to adjust to this new situation.

Why should they ever meet. They have nothing to do with you.

From your update, I would wait until there is an agreed way forward tbh. Your@ eldest DC needs more stability than an NT child.

In my head I would have to separate the whole thing from my life with my son and young baby to stay sane and I would think that my ex husband has to manage his own life and new decisions and how they impact on my son, however hard this is to do. If your son doesn't enjoy being around his dad and new partner, and eventually new baby, the visits will get shorter. I would just make my son feel extra special while he was with me as he will be dealing with so much. Sorry you are going through this.