79 Year Old Father and Dementia?

Our Father is 79, he has faded in the 5 years since our Mom's ping. He spends 12-15 hours a day at a local gambling casino. His finances are a mess and he is almost penniless. We are very concerned and asked if he needed help to pay bills, etc. He got extremely belligerent with my eldest brother and I. He lives 5 hours away, refuses to move home and we don't quite know what to do. He won't even consider moving to a retirement community, so we don't know what if anything we can do. He won't spend time with any of his children or grandchildren. Can we force him to move closer to us so we can take care of him? I am so upset and confused with all of this. I don't truly have a Dad anymore and I don't know how to reach him.....HELP