Unwrap UVW altered with edit mesh, please help

[matchley]

I have a heart model, lovely Zygote model with perfect materials mapped with Unwrap UVW.

 

I had to make an incision in the heart and combine the interior and exterior meshes, now the Unwrap is now a complete mess. I have no idea how to fix it.

 

Here is the model:

 

Here is what the Unwrap window looks like:

 

By combining the two parts, the unwrap fused together and I cannot figure out how to separate.

 

Thanks in advance!