She chocked her kids am I wrong?

Please read post to understand**** also Thankyou for your responses.

My fiancé mother abandoned him when he was 12 he’s 23 now and she just came into his live about 6 years ago and sh is in and out she is a druggy she claims she’s off now but we have all heard it before. Anyways she is visiting and I allow her around the kids only with constant supervision because she admits to chocking out all of her kids before from ages 0-5 she chocked all of them out and when they woke up she told them “I brought you in this world and I can take you the fuck out” so yes she is not aloud around them without supervision my fiancé and I agreed well I get in the shower before I get in I double check that he will watch them and he agreed I get out I hear her and not him I look downstairs and he is no where to be found I call him hesin the bathroom I know he takes like 30 minute dumps so!!! I told him we agreed and he said he had to go but if that was the case why couldn’t he bring them upstairs with me? He could have put daughter in crib and son with me he has done it before when she wasn’t here. Anyways that’s the start so I try to sit around with kids around her but she says annoying off the wall shit and she rude I can’t handle it so I leave for the day (this is where shit gets crazy)I let her spend time with the kids at night she is leaving tomorrow and asked if I would let her have the kids next time she comes down in December I said not by yourself she rolled her eyes and says no not alone and I said well bob doesn’t stay around and watch them when your around like he claimed he would so probably not and she was like why is it an issue why can’t I why are you so afraid to leave them around me I was like you said you chocked all of your kids out and she says whatever you say Kayla. I was like you did she goes nobody is arguing with you whatever you think I said I was like what do you mean you fucking said it nd bob was right there not saying a word so I was like did she not???? And he was like she didn’t say she didn’t choke us out I was like she just said whatever I think she said (she was trying to lead on that I made it up like okay whatever you think I said whatever you say) she was trying to fuck with me anyways I start telling bob why is it when your mom comes down you act like we never had this conversation now that your in front of her you act like you didn’t agree not allow kids to be alone with her and then his moms husband steps in and he was like why do are you standing there talking?? I was like I am talking to bob not you remember you are a guest this is my house. And he was like well you are talking to my son! I didn’t say anything back but I don’t see why that mattered on who I was talking to why even get in the convo??? Btw not is son he was in my fiancé life for three years at most until they abandoned the kids and he recently got back with his wife bobs mom not even a year ago!!! So in total he has been in bobs 23 year life for 4 not consistent years and all of sudden bobs his son 😂 anyways if that was the case why does it matter if I am talking to bob he is a grown ass man I was talking to him not you. And bob didn’t say a fucking word to defend me just had me standing there looking dumb. This is not the first time.