I have the puppy blues really bad and don’t know what to do.

So I got a puppy yesterday and have been feeling miserable since. He’s a sweet boy just very energetic. I feel so guilty that the main thing I have been thinking since getting him is how I want to return him. I have read through so many posts of people saying it gets better and I know it will but I cannot stop crying and feeling exhausted. I came into this feeling so prepared and knew that it wasn’t going to be easy but I never imagined I would feel like this. Last night I was up for hours having a panic attack in bed. I just have no idea what to do. My partner has said it is hard but doesn’t feel the way that I do so it’s hard to really talk about it. I just feel so stuck and scared. Please if anyone has advice on how to take care of themselves during this time let me know. I know I can get through this I just cannot get past this thought that I will mentally be better if I just take him back to the shelter where I got him.