Although it is possible to get grandparent visitation rights in Colorado, it is very difficult. This quote from the US Supreme Court sums it up best:

“In an ideal world, parents might always seek to cultivate the bonds between grandparents and their grandchildren. Needless to say, however, our world is far from perfect, and in it the decision whether such an intergenerational relationship would be beneficial in any specific case is for the parent to make in the first instance. And, if a fit parent’s decision of the kind at issue here becomes subject to judicial review, the court must accord at least some special weight to the parent’s own determination.” – Justice O’Connor, Troxel v. Granville Opinion

It is very difficult for grandparents to get visitation rights over the objection of the parents. It is possible, but typically only for cases where the parents are not fit to be parents in the first place. Given your father-in-law's anger and aggressive behavior, it is all the more unlikely.

For more information review our articles "Grandparent Rights in Colorado" and "Child Placement with Grandparents."