Also a theoretical question:
Why are so many men so hung up on last names...
You can be a good dad to your children, and their love for you will not change with the change of their name (should it ever get that far).
Not sure how old your children are, but should your wife ever remarry, it might be difficult for them not to share their mother's name any more (who, I suppose will be taking care of them).
Maybe it won't be a problem, who knows, but is this name more important to you, than your children's happiness?
Just a theoretical question as I said!
Other than that:
A friend of mine had her son's name changed (to her maiden name) after she split from the father!
I know she never got his consent for this, so not sure, what the law says on this!
And other than that:
I wish you all the best for the future, and hope you can be the great dad you want to be.
And I hope that you and your wife BOTH will put your children first, and your personal problems only second!