mog - Drama Normal?

Guys...I’m a little disappointed to sharing this but I feel I need some support. I have been dealing with MOG constant drama throughout our engagement. Recently she reached out asking if i had a few minutes to talk to her about the wedding shower and I told her I thought her and my mom were going to work out the details and plan things under my mom’s direction. My mom is the maid of honor and she knows and supports what I want for the wedding shower. when MOG takes charge she tends to cause drama and fight with things that aren’t along the lines of my vision , etc. previously before she reached out she called to complain about something and I told her afterwords that It would be best she reach out to my mom directly because she’s running it and they can work out who will do what. I also explained I did not want to be put in the middle and the messenger person of frustrations which she does a lot even to her son and things would escalate. Anyways so after I told her that I thought she would be discussing things with my mom she didn’t respond and I thought that was the end of it. At around midnight I get a call from my fiancé that she was pissed that I didn't answer her question. I told him I did answer her questions and sent him a screenshot of the texts. he didn’t understand because she told him I didn’t answer her question about our registry and she never asked about the registry. I was a bit annoyed after this because it is just way too much drama for something so silly especially. He doesn’t like that she lied to him to make a big deal about something and to cause drama for attention. This morning she sent me a text saying “I can’t do the 30th anymore so I gave the bottle paintings to him for you two to finish up” I responded and said I thought we made plans on the 30th to do that together. She then said “Not anymore”. I figured she was saying this because this is just how she is. She is a very passively aggressive person who I’ve come to see that she likes to always act like a victim, lie and manipulate people to take her side and for attention. I sent my fiancé the texts and he is really annoyed that she is acting like this. He called me after receiving my texts and told me that around 6am and 3 other times after that she raged into his room yelling at him and he finally snapped and yelled at her saying “what the hell is wrong with you”. Then she took out her anger on his dad. My fiancé doesn’t even want to sleep at his own house or be around her because he is fed up and doesn’t like what she did and how she is talking to her future daughter. Even if he tried talking to her he knows that it would get escalated into even more drama (offended & would flip out) if he told her she can’t act like this and behave in such a way. From my understanding his mom has always been this way with a lot of things. She didn’t start acting crazy like this towards me until we got engaged. Now it’s like all she wants to do is fight or something. I have talked to my mom and she reassured me that she is really only causing problems for herself and to not let her issues bother me. I’ve been bothered by it I won’t lie about that but I do feel stronger in the sense that this is her stuff she’s taking out on others. Has anyone else delt with this kind of thing? I’m not really sure I even can deal with her anymore it’s just I don’t really feel like she is a good person to be around or be involved with which is difficult because I’m marrying her son however would like to keep my guards up and a distance from her so I don’t fall into her trap so to say. My mom thinks all of this is not normal at all.