Maybe talk about it with your mom before hand, like for if he interrupts you then you both stop talking, wait for him to stop, ignore whatever he said and continue your conversation, or once he's done ask/tell him to wait till you're done talking to start another conversation/interject. Maybe bring up how he insisted therapy & that this is an example of something he can work on improving to show he cares. Of course you know your situation best so you would have to edit how & what you say to fit the setting, but I hope this helped somewhat or at least gave you an idea. Im not sure I could've had this talk at all with my dad so I wish you luck !!!