It is quite likely then that your wife’s email account will also vanish soon again with no notice. What should happen in theory doesn’t always pan out in reality, the history of the Virgin.net email accounts is a little confusing. Many years ago there was a dial up internet access provision also confusingly called Virgin.net and later an ADSL service with the same name. Customers of these were allowed to create and use an email address ending with @virgin.net on certainty conditions, ie that they used the dial in provision regularly Virgin received a proportion of the telephone fees for this, or that they continued to be an ADSL customer.
Back in 2014 or so VM closed the dial up service and the following year sold off the ADSL service to TalkTalk (cue many years of confusion over responsibility for the virgin.net email addresses), anyone with such an address were given a year to migrate their email to another provider OR if they could sign up to a VM cable broadband account then they could continue to use it, not everyone was in a cable area so this might not be possible.
However in some cases the legacy .net email addresses weren’t closed down after a year as they should have been and simply lingered on, similarly for some customers who did take up the VM cable offer, the old .net email addresses were not properly associated with this account. Some users left VM but found that their old addresses still worked and carried on using them.
However these addresses were always on borrowed time, VM run periodic sweeps or cleanups of addresses not associated with live accounts and when found, unceremoniously lock them and then delete them. This might sound a bit harsh but VM will, not unreasonably, point out that, well you aren’t paying them anything, and they did tell you back in 2015 or so - what you didn’t read the small print of the agreement? - that this would be the situation and you have been getting a ‘free’ email service for all this time, so you can’t really complain. Alright, yes, maybe it could have been handled better, but it is what it is!
OK, best to work on the assumption that your email address has gone and isn’t coming back, your wife’s if likely to go the same way at some point and make alternative arrangements.