<human>: Can you provide a brief overview of the text?

*title should say [27F]

As the title says, my BF's best friend is cheating on his pregnant gf. Best friend will be Mike, gf will be Kate, neighbor is Jill.

Mike has been dating Kate for a few months and their relationship has been very rocky--constant breaking up and fighting. Now Kate is pregnant for him (he thinks it's not his but w/e). Mike has never been faithful to any girl he's dated that I know. He's cheated on Kate with two girls so far; she found out the first time because the girl he cheated on told her. Kate blamed me because she thought I knew about it (the girl was my best friend), but I didn't. She told me if anything like this happens again to tell her.

Now presently, Mike is cheating on Kate with our neighbor Jill. Jill recently ended her engagement to date her ex-fiances best friend, whom she's still dating, but now she's cheating on him with Mike.

My dilemma is do I tell Kate? I feel so bad for her because last night Mike left her to come sleep at our neighbors house, and they were talking so much shit about her while she kept calling him.  I want to tell her, but I don't want to cause drama. Jill is also my BF's cousin and the daughter of our landlord. I just know that if I was pregnant and my BF was cheating on me that I would want someone to tell me. What should I do?!
<bot>: Friend of BF is cheating on his pregnant GF for our neighbor(also cousin, daughter of landlord, and in a relationship with someone else). I feel really bad for pregnant GF, do I tell her?