Does anyone else have to complete others sentences/interrupt to continue a conversation…? 

My boyfriend got upset with me for doing it again and I kinda freaked out because someone being upset with me = hatred (in my brain anyway)
I notice that It upsets me when people give half assed responses like “yup. Uh huh. Totally” so I’m assuming that’s why I finish people’s sentences. As a way to say I understand… 
But no one likes it, I don’t know how else to communicate, and I’ll often drift off into dissociation-land if I try and stay quiet and then here comes the “Huh? What’d you say? 🤷 “