Wow - that's truly shocking. Can only begin to imagine how poignant this task was for you - and then to be faced with unprofessionalism, rudeness, insensitivity and, arguably, racist remarks "all these foreign names" is just disgusting.
I'm not a registrar, but any idiot knows that sensitivity must be applied to the task. For example, when dealing with people registering deaths. It's also legally imperative that all details are correctly recorded - so her suggestion that there was "no point" in recording your late husband's name was both crass and questionnably illegal (as a previous poster also suggested). It is not "just doing her job" to be disrespectful and cruel, quite the opposite .... and remarking on "all these foreign names" is none of her business and implies she thinks "foreign" names are, for some reason, less valid and/or worthy than so-called "British names".
In fact I remember seeing a job advert for a registrar some time ago and sensitivity was definitely one of the required personal skills !
When you feel able to, please complain about this hag. There was absolutely no need for her to be so unpleasant (your account made me imagine her as a grotesque character from Little Britain) and then there is the issue of her failing to do her legal duty re: your husband's name on the certificate. (I presume you insisted ??) Again, I'm no lawyer, but there must be a variety of potential legal scenarios where it's very important that a child's father is recorded as such - whether or not he's still alive.
So sorry you have had to go through this.