Help: I think I'm supposed to use Aggregated Devices, But it's not working?

So here's the deal.

I have a midi keyboard plugged into my iMac. I have a standalone program that can play piano. I can play it fine. So I wanted to have what I was playing being outputted into a chat window online.

So, the audio input settings in the chat did not have a regular built in audio selection. So I got soundflower! It recognizes soundflower just fine, and it willl output. BUT, when I export via soundflower, I hear nothing on my end (built in input).

So I thought, I can set up an aggregated device that plays both soundflower and built in input, and then select that aggregated device in the chat.

But that did not seem to work.

So ultimately, How can I output via soundflower but still hear it through my built in input?

 

Anyone...?