Am I the asshole? Or is he? Very long

My SO and I seem to always be at each other’s throats. We’ve been arguing a lot lately, but even since quarantine our lives haven’t changed much so it’s not because of that... I’m almost 20 weeks pregnant with our second child so I’m super hormonal and emotional and need to know if I’m being the asshole here... little backstory. We have two cats and a puppy together. Well, he has a cat and dog, and I have a cat. My best friend is living in her moms basement right now and was needing someone to watch her two cats while she and her boyfriend found a place to live... I talked to my fiancé and he said he didn’t mind. They have been here way longer than they were supposed to be, and I take full responsibility for that and can understand why that would frustrate him. One of her cats developed a UTI and hasn’t been using the litter box (on meds for it). I clean up the tiny little spots she leaves whenever I find them or see her doing it. He threw her in the shop and got angry with me. But His puppy can roam the house, eat mine and my daughters shoes, her toys and anything else, pee in our bathroom floor and poop in our bedrooms. And he just brushes it off like it’s no big deal and cleans it. Well tonight I told him his puppy had peed in the floor. He then very rudely told me it wasn’t pee, the toilet was leaking. (It has never leaked, I promise it wasn’t the toilet) I told him it was yellow, it was pee. And he got very defensive, repeating my words back in a mocking tone. I set my stuff down and just said I was going to bed, and grabbed our daughter. I was walking away and he goes “good, I’m tired of dealing with you today anyway”. I’ve been bawling ever since and would just like some outside input. I know I’m moody and such right now, but I feel he’s being unfair.. and I suffer from depression so I’m also not sure if that’s making it seem worse than it was or if he’s just being rude.