Does she really love him im worried shes using him. what can i do ?

I don't think she is genuine. She tells him she loves him because it's a cheap word that can yield her such a huge return, and maybe an UK citizenship in the future. Best you could do is show him a whole lot of international marriage fraud cases maybe, but if he is so into her, no one can really stop him from pouring all his money onto her rather than his kids' education etc. He will learn his lesson the hard way sooner or later.