Calling somebody else fat won't make you any skinnier.
Calling someone stupid doesn't make you any smarter.
All you can do in life is try to solve the problem in front of you.
Some people are just hateful and insecure and lash out at those whom they think will let them get away with it.
Look at people on this site who, unlike LadyDiana's posted style, personally attack/drag other people whom they don't like, or even people they just know other people don't like, for the "kii" of it, without even really knowing them.
They clearly have issues, and the 'friend' similarly being disgusting has their own issues they should deal with, and you should just know that such people are the problem, not you.
They sound jealous of you. I had a "friend" do the exact same thing to me too. We were best friends for like 10 years. After I bought my house they got all jealous and expected me to pay for everything because I was "rich". I cut them off faster than Beyoncé Slays the world. Then I purged everyone I didn't need from my life. I suggest you do the same
Like, if you see someone's selfie and the first thought is to say something negative, what does that usually mean? If it isn't clear, the person is jealous of you and has to throw some type of hurtful "shade" to make you feel what they are feeling inside... Anything indirect usually stems from some hateful inner **** that that person is dealing with.
The best thing you can do is not be discouraged... Tbh, don't even block the person. Completely ignore them and continue to upload your selfies.. Don't respond in anyway.. and if you do anything, silently send good vibes to that person because they clearly need it. Insecurity ruined social media, seriously.