Making effective use of SIMD instructions without moving whole app to c++?

I want to use SSE2 or similar instruction sets for simd to improve performance in my application.

My situation is this:

I've written some code for the app in c# but I don't mind porting if it's necessary. C# does not inherently support simd.

I have never written anything in c++, however I have written code in C before and therefore understand many of the concepts of c++ and I dont think it would be too hard to learn.

I'm looking for a practical decision on which tools to use. Do I continue with c# and interop with c++ on only performance critical functions? This wouldn't be ideal I think. Would it be better to switch to pure c++, or is there another alternative?

Also I'm good with java too.