“Per my divorce decree, my ex was to maintain the premiums on his life insurance policy - he never did, so I paid the premiums each month. He has now passed away and I want to know if I can now collect any amount of the premiums that I have paid for the past 14 years, from his estate?”

You may have a claim against his estate for the unpaid premiums. There is a process for submitting claims to the Personal Representative of the estate, and if that claim is not paid, for filing suit against the estate. The fact that you slept on your rights by not enforcing the order that he pay the premiums for 14 years may work against you. You may need to speak with an attorney skilled in the area of probate law.