Not sure what to do

It feels like my life is going in a downward spiral. My mom told me on Wednesday that we have to take my dog to the animal shelter next Saturday. I have had this dog for two almost three years, and I have had him since he was only two weeks old. It’s not only the fact that I have to give him away, it’s the circumstances I’ve been put under. He’s only leaving so fast and basically without notice because my sisters boyfriend is a jerk who thinks that my dog will harm their baby which is such a lie. My dog doesn’t even know what the baby is. And he is putting this pressure on us to get rid of him and if we don’t then he’s gonna call cps and take full custody of my sisters baby. And I don’t want that to happen. But it hurts because I have to get rid of someone that I love with all of my heart. And what makes this worse is this is all happening in the month of March. My friend passed in the month of March and I’m not prepared to go into this month let alone get rid of my dog this month. So I asked my dad (I’m not on too good terms with but we still speak) if I could stay at his house for awhile because I don’t wanna see my family throw away all his toys and his bed. That’s gonna hurt me even more and my dad said that it’s okay and I can stay over for as long as I want to and I couldn’t stress to him enough how much I wanted to leave that day. And he said he will make sure I get picked up either by my brothers on his side of the family or by him. And I told my mom this and I honestly thought she would be mad but she wasn’t which is good. I guess my point of writing this is, I’m not sure how to cope with this right now. It’s a struggle to go to sleep no matter how tired and exhausted i am because I keep thinking about what I’m supposed to do with myself after he leaves. He’s my only friend right now. My mom wants me to go with her when she takes him to the place and she’s like “It can be just you, the dog, and me. Nobody else has to come” but I don’t wanna go because that’s gonna be really hard to do. This all honestly sounds like a dream because I have some how convinced myself that this isn’t happening and it’s not real