I'm glad you had the good talk with your MIL, FS. The birthday dinner sounds sad, and difficult, but also a bit of a watershed moment - you've had that experience now, and next time, if you choose that there will be one - will be better. And things are thawing with D13 too. Everything is moving, very slowly, into a new normal. Eventually the family birthday dinners and different sort of relationship with MIL and perhaps even a more friendly relationship with H will evolve very slowly.
I have rib cage tattoos. Two very large ones: a lioness on one side and a lotus on the other. I've also had a natural childbirth and I don't think the tattoos were that painful, but they were definitely the second most painful. It took three hours!