Dita
I agree that op has the final say as to whether she goes through with the pregnancy or not. If she values her relationship, I do think she should listen to her partners opinion and bear it in mind though- that is not to say she should just do as he wants and ignore her own feelings. Merely, that if she wants to remain in a partnership then whilst she gets the final say, it doesn’t bode well to declare that not only does he have no right to an opinion but that he is to be told how he must feel about it AND how he must behave (reassure her that he loves her, will support her etc).
The reality is that if you tell your partner their views don’t matter, only yours count, and this means they have to put up and shut up, whilst also being accepting, loving and supportive- because that’s what you want/need, then you have to accept they might decide to re-evaluate the relationship too.
Ultimately, OP gets to decide whether to have a termination or not, but she doesn’t get to decide how her partner feels about it all and demand he behave in the way she would like (though obviously he must support his children financially and be there for them).
It would be better if this were viewed as partners trying to come to a joint decision (with the tacit acknowledgement that op obviously has the final say) rather than a confrontational “My body, my choice so his feelings are irrelevant and he must just do whatever I want AND support me 100%”.