Should I tell my partner or friend I am a recovering addict?

Yes you should. If that partner or friend means much to you and is a big part of your life, and you consider yourself a big part in their life, they have a right to know this about you an they should support you too.

Definitely tell your partner, if they happen to find out later, they'll blame you for being untrustworthy and secretive.

It's best to be honest from the start. You have taken a huge step to firstly get help for your addiction, congratulations on that, its not easy for someone to admit that they have a problem and seek help. During this process of recovering you would need all the support you can get, it would be good to start with a friend.

In my opinion, it's important to have a very high level of openness and honesty within a romantic relationship. I think it would be a mistake not to tell a romantic partner that you are a recovering addict. Your partner may feel betrayed, lied to, or hurt that you didn't tell them...especially if they find out when/because you relapsed! As for a friend, I think that the answer becomes more nuanced. Not every friend has to know everything about you, but certainly it's helpful to have at least one friend who you can be open with in this way, if for no other reason than you may need their help one day, and they will be happy to help if they know about your addiction.