How do I tell my friend she is crazy?

Okay, so......

My friend has been talking to a guy on the internet. Madly in love, doesn’t even know his last name, the country he lives in, or what he does for a living. They have never video chatted. Every time she asks theres always an excuse. I have told her this is not a relationship. She is about to be 23 years old and acts like a child. I just want her to be happy. She put on over 100lbs due to medications the doctors put her on and since her self image has been terrible. I offer to work out together and diet together ( i wouldn’t mind losing a few pounds myself!). She wont do it, all she wants to do is eat and sit on the couch being obsessed with things 12 years old would be obsessed with. She can hardly leave her parents side. This is just insane though. She always wants to go back to the same guys that it never worked out with before wether they cheated or broke up with her for her anxiety problems or guys from other states or even countries!!!! She always comes back crying to me and I try to be there for her but I am slowly losing it. She needs to grow up, i have tried being nice, bluntly honest. Even her 16 year old sister tries to tell her what she’s doing doesn’t make any sense and isn’t right or good. I’m just stuck. I just want the best for my friend! I’m afraid if something happens to her parents and she doesn’t start seeing the world for what it is and not some fairy tale she is going to really lose it. Any advice would be helpful! Thank you so much!

Also, I don’t actually think she is crazy and she does have depression! I’m just really worried about her. I’m not sure what I can do for her. I have no way to get ahold of him. He only has a dating app and snapchat which you can use other pics on too.

ADD: she already goes to therapy and a psychiatrist and sees them regularly and is on medication. We have been friends for 10 years so I don’t want to throw our friendship away, I want to help her! I am very honest with her about things to the point where it almost sounds mean but its just being honest. I’m not actually mean about it though.