How bad is this tattoo going to hurt?

Any placement where the bone lies close to the surface is going to hurt more than a place that's mostly muscle or fat. Fine work also hurts more than shading. So yes, it's going to hurt. You might even have to take a break or two. I have one on my ribcage and I had to take a few minutes halfway through to have some water and fight down the nausea and urge to p out. LOL... But lots of people have that happen, even the big tough guys sometimes. They just don't like to admit it. So don't worry about having to stop every now and then. You'll get through it.