Is it weird my Dads Ex tries to be my friend?

I met my dads girlfriend a few months ago and we really get along since I’m 20 and she is 31 so not much of a difference. She messaged me sometimes and sends pics and posts us. I didn’t know they broke up the other day and my dad said to her to leave me alone as she done something bad which I had no clue about and he didn’t want my family to be in touch with her.

the other day I had a argument with my mom so she came and picked me up and let me stay round her house for a few days. ( I had no clue they were broken up until she was crying yesterday when we went clubbing since he didn’t reply to her message ) .
I really get along with her though she was like my best friend but now my dad is saying that I can’t see her anymore since he thinks she’s PURPOSLEY trying to get close to me so he likes her again and she can find out info? Is he being dramatic here? I would like to speak to her but he thinks she’s trying to manipulate me so she can get him back. ? Would I be in the wrong to speak to her again?
Is it weird my Dads Ex tries to be my friend?
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