everything you say here points to the fact that it is your dh that wants this termination. Your dh is definite he wants a termination; you're afraid that your dh will resent it if you don't have a termination...
What do you want?
not what you think is the right thing to do, what is it you actually want?
Ultimately, no-one can force you to do anything you don't want to do. So you have to ask yourself, what is it you do want to do?
Do you want a termination? Because if you don't then you will be the one that ends up resentful.
Is it that you don't want another baby? (which is understandable in the circs), or that you don't want this baby? Because there is a difference.
As things currently stand there is already a baby. If you proceed with this pregnancy the baby will be born and yes, things will be tough, with more sleepless nights and another mouth to feed and your family dinamic will change. But sleepless nights are not for ever, and there will be an end in sight, and as you already have three kids it is unlikely that this particular baby will be that unwanted. It's not as if you're a teenager unable to cope.
But if you terminate this pregnancy there is no going back.
So if you terminate the pregnancy then it has to be because that is what you want to do. You can't do it for anyone else, not for your dh, not for your other children, you have to do it for you. It is you who has to go through the termination, or alternatively carry and give birth to a baby you potentially don't want.
You can discuss it with your dh, but at the end of the day it is your body and your choice, and only you can decide whether or not to go through it.
good luck.