Also, you can contact the Embassy that issued that visa to confirm its validity.
But be aware that many scammers commonly prey on older western men, since they are considered to be a pretty easy target.One of the requirements for the fiancée visa is a personal meeting within the last two years.And YOU will have to file lots of paperwork before she can even fill out her application. In any case, do not send any money without verification of the validity of her visa.To see what kind of person you are dealing with, you may just mention that you are in a bad financial situation yourself and would love to help her with money but cannot do that at the moment.If she is genuinely attracted to you, as she says, then she will understand.
Do not send her any money, offer to buy her a ticket instead. Even if she writes to you that an airline ticket would cost two or three times less in Russia (which is questionable) , do not send her the money! Most likely you are being set up for a "visa and tickets scam" when a bride asks you for money to pay for her tickets and visa and then disappears once she gets it. Ask her to provide more details on the University that she is going to come to study at, and then contact that University.