Fellow is not your friend. During 15 years there was ample opportunity to discuss beliefs... If a person does not value, respect or trust you enough to share his beliefs, be honest about what willing or unwilling to do, agree to disagree, work through a problem, whatever then an acquaintance at best. Tough though as 15 years is a lot of history but quality over quantity. If that is the type of person it is and not a misunderstanding then run the risk of them saying one thing and doing another or otherwise screwing you again in the future... Consider the risk this person posses to you when you have your license and possess firearms, can you trust them with a key to your place...
The experience serves as a warning though, can remove this person from your life but may be more difficult to remove people at work / in other relationships and it was just made clear how a person's beliefs need not be rational or open for discussion thus may be need to exercise some discretion... (3, 2, 1, waiting for the flack about need to be an advocate and not hide firearms ownership... would ask if are an advocate for your beliefs on religion, politics, abortion, prostitution, drug legalization, etc. in same circumstances...).