With a C# background you're probably rather familiar with the .NET framework already, making that even more attractive here.

You're right, C++/CLI is the preferable language when it comes to integrating native libraries into .NET apps (and the other way 'round, but that's far less common) but the "contact surface" between the two worlds should preferably kept small, minimizing the frequency of rather expensive managed/native transitions.

There are quite some threads around here discussing library wrappers used in this kind of integration scenarios, which may at least give you some first impression of what that's about.