Dog advice

My husband and I have 2 bigger dogs and one little dog. One of the bigger dogs his name is diesel, he’s a walker mix and we got him as a puppy when we first got our own house together. Kind of makes him sentimental to me🤷‍♀️ and I had the little dog ever since I lived with my parents so he came with me when I moved. well about 2 months ago my husband hit a dog that ran out in front of him on the highway so we took him, cares for him and no one ever claimed him so we kept him and he joined the group and we named him hunter. Diesel and hunter got along very well and LOVED each other we only have a small fenced in area so they loved having some company as we keep them in the small fenced in area most of the day sometimes they come in and they are in deprecate kennels while we sleep. Neither has ever been aggressive but last night my husband and I were eating dinner and heard what sounded like dogs fighting. My husband ran back there and there was blood all over the back porch. It was coming from the one we picked up on the street (hunter) his nose was bleeding and he has a place and blood coming from the side of his mouth. I will post a photo of it. I don’t know what caused them to fight neither has ever been aggressive. There was no marks on the dog we got together when we first got our own house together (diesel) my husband said we are definitely getting rid of diesel to find him a good home as I am 32 weeks pregnant and he said he didn’t want a dog like that around his baby. I’m stuck and don’t know what to do and asking for advice I guess??? Should we just keep a eye on him and not give him away since he’s never been aggressive before because I would be heart broken to give him away or to take him to a pound. But if it’s unsafe for my baby of course that’s my number one concern. Thank you for reading all this if you have gotten this far!