Roommates

Dr
Looking for some advice. I live on a half acre that is not super well fenced in, it's wire fencing but there's land all around us. Except for the driveway to which leads to a busy main road. 
My roommates (we have one set, and we also live with my mother in law, but not like it's her house, rather that she's an additional roommate.) got themselves a corgi puppy a year ago, and since they both work full time jobs they have to leave him cooped up in their room with their two cats most of the time. When they got him they asked if we could take him to go potty from time to time, so we agreed for the sake of the dog. Well he's a little over a year old and he's pretty used to our routine, he barks like crazy and loudly until we take him out and then he proceeds to take his sweet time and what not, but when dealing with my daughter we don't always have time to walk him around outside. I mean this dog will take up to 30 mins to poop and if you take him in too early he's poops inside the house, usually my daughters room if left to roam free inside the house which we allow sometimes due to feeling bad for him. The cats don't like him and they gang up on him sometimes. So our solution has been to let him roam freely in the yard until he's ready to come in or they come home since he refuses to come when called. If I can't keep a close eye on him for whatever reason we shut the gate that blocks driveway that leads to the main road. This hasn't been a problem...Until tonight. Tonight Alyssa comes home and freaks out that I left their dog outside "in the cold", I was taking my one chance to take a shower so I didnt know this until my mother in law informed me. Well her boyfriend victor comes home and confronts me on it. He wasnt rude but he wasn't all that forgiving either. I just feel like their whole reaction is out of line. And I feel attacked. Why is this suddenly an issue? My mother in law and husband have been doing this for months. Why am I the one getting in trouble all the sudden? Still i apologized for upsetting him and held it togather till he left the room and then I went into my room and broke down. The dog needed to go to the bathroom, and his barking was going to keep my daughter awake who I just put down. I don't even know where the leash is kept and don't want to snoop the room and the damn dog is thrilled to be out of that room. That's why he takes so long. How is my leaving him outside for abit "in the cold" any more cruel than cooping him up with two mean cats for hours on end? (Mind you the coldest it gets here is 45 degrees) I understand the concern that he might get out, but like I said we've BEEN doing this? Why didn't they speak up before?? 
I'm so frustrated. I'm not sure what to do. And I very much feel like they are in the wrong. I don't know how to handle this any further. :/