If there is someone in your life who you have been friends with for a very long time then they should be sympathetic. Maybe you could show them this website or print pages off to show them so they know you are one of the four million paruresis suffers in the U.K.
They are less likely to think negatively towards you and your problem then.
I am in my 40's and have had paruresis since about 25 years old. I too have had leakage problems and told a mate who then told me he has the same. I told somebody else then and he said the same too as did a younger guy in his 30's who was next to us.
I have tried "exposure therapy" (as it is medically called") too by going to swimming pools and walking around naked hoping it would de-sense me at urinals but it didn't work. I have been seen by loads of men and just think to myself "So what... we all have the same and we have all seen another man's at some point in our life because it has been unavoidable".
Wishing you the best of luck for the future.