Any advice please?

My friend had been acting very childish lately. She does and say disrespectful things to me all the time and I don’t say nothing about it.

I don’t want to argue with her because she my friend and I know she finna make me feel like I’m overreacting but me not standing up for myself, she going to continue to walk all over me.

I can’t just stop being friends with her because it’s three of us Yk, the Three musketeers lol. It’s just going to cause so much drama, I don’t want it.

Recently she made a groupchat with my ex and another person. I don’t know how I should feel about it. If I ask her about it she going to think I’m jealous over her. I feel like she already thinks that.

You could leave the group chat is it makes you uncomfortable. You mentioned it was the three of you, so I'm assuming that means you also have another friend in your group. You could ask them if they also notice her childish behaviour and perhaps she'll listen if both you discuss it with her.
What specifically do you mean by 'childish'?

Oh it’s just my friend and my ex in the groupchat and someone else. I’m not in the groupchat at all. My friend and my ex havent spoken in years, so I feel a little disrespected or I’m just overreacting. My other friend also notice her child behavior which is her doing things to get me mad.