RANT - This dog is killing me

We closed and moved into my husbands grandmothers house a month ago because it was gonna foreclose and go outside of family... and she wanted it to stay in family but no one else could afford it... so its our house now. We bought this house and agreed to his grandmother and her dog (small sized poodle) living there on the 'told to us by everyone' notion that this dog used pee pads in a specific spot of the house to use the restroom because it can't go outside or itll run and grandmother doesn't want to risk catching fleas on a two-minute bathroom break.. Unbeknownst to the entire family, it doesn't. It literally uses the bathroom anywhere it wants to, specifically our bedroom downstairs, the living room and upstairs in my kids rooms. We have to keep all the doors closed or risk a steamy pile of crap on our once nice carpet to pick up ourselves. His grandmother knows I absolutely hate indoor animals for this reason and agreed to all of this on the notion of a designated usable space. I can't say I haven't thought of leaving the front door open a few times. Its been expressed several times that she needs to use the pads and even her own daughter was visiting the other day and lost it on the dog because she ended up stepping in crap. His grandmother simply makes excuses and refuses to do anything and my husband is too scared of upsetting her to say anything even though he hates it too.... Not to mention if you sit in a room and get up it will bark at you and chase you down because, as his grandmother says, she has to control who leaves and when. I also have a newborn that she keeps getting on top of and sniffing on and stuff (even tried to sit in him once) if I'm not careful. I understand she may have run this house once, but its mine now and she isnt running anything anymore. I'm literally at the point of punting this dog across the room. Im just done...

Also, to add insult to injury, when we first moved in and she was pooping on everything, his grandmother tried to act like she never had an accident like that before and she must have had a stomach problem. In my head I was like, dont lie to me like that, I see all those stains all over this expensive carpet I'm now going to have to replace when she's gone...