First, you need to be absolutely sure here or poof breaker pop. Do you have a Volt Meter?
You don't have before pictures, do you?
I'm trying to understand the photos you've provided. In the top photo, there are just two wires in the pigtail- right? A pair of black/hot?
Also in the top photo is a pair of blacks and a single white going to another pigtail, which you show in photo 2?
I would be looking for a pair of wires that go out to the switch. That white is a dead give away of a 'runner' for a switch run/return- so one hot out to the switch and back on the white (or in this case, the black!) (should be color coded / sharpied though to make sure).
This is what I think you have- the 2 black pigtail is the switched hot, the return. If you can confirm that the 2-black pigtail goes into the same romex as the white that is tied in with the other 2 blacks (BBW pigtail), then I think it's safe to say that that is a 'hot' and a feeder to additional circuits.
If that previous paragraph is correct, then yes, all you'd need to do is add an additional black off the BBW (making it BBWB) to the single outlet.
It's not nearly as hard as I'm making it but I'm really having trouble tracing the wires from the photo. Best bet is to have the power off and confirm the switch runner pair via continuity, and then (capping the wires to be safe) test which wire coming in is 'hot'.