The last time this happened to me, I did this:
1. Remove broken glass
2. Use a rocket blower, gently blow off tiny glass "powder"
3. Use a pair of multigrip to clamp onto the filter ring, then twist the filter ring to make a big "S" kink into it to reduce its diameter. By repeating this on opposite sides of the filter ring, the filter ring's diameter is much smaller, allowing you to remove it.
The lens I used this technique on? A 180 f3.5 macro lens, and it's been 4 years on, still going strong. AF and MF are still both spot on.
