Affiliate Marketing Secrets

I have two friends, and one friend who I am really connected to, we have deep talks and we talk alot. Then I have another friend who I hang out and often sit beside. The problem is, the friend I hang out with (Alex) is what I would consider a bad friend. I can’t seem to say “no” to his requests and I usually treat him nicely, but he doesn’t hesitate to treat me badly. Then I have my other friend, who for this example is going to be called Mark. Mark said he was going to cut off all affiliation with me, since I am affiliated with Alex. I now only have Alex, and my other friend Mark is not going to be for me until I remove my affiliation from Alex and establish my own way.
I believe that a true friend is one who stabs you in the front and is completely honest with you and how they feel about you and how they want you to change. I see this as Mark trying to change me and getting me to cut off affiliation with my friend Alex, which is what I want to do. What should I do? I really value my friend Mark, but I can’t just go to Alex and say, bye gtfo, done. Alex considers me and him very close, but I value Mark more. What should I do to resolve this?