Help on concave collision

1

well i learned how to triangulate simple polygon into smaller triangles,but i still got a problem with the reaction. To bounce an object back after it hits another object with convex shape,i used the separating axis theorem.but if i triangulate a concave shape and its divided in to many triangles,and when an moving object hittings its,if i use the SAT to do the reaction sometimes i might just be bouncing between the 2 triangle inside the shape(depends on where the object hits).any one know how to handle the reaction?