Having extreme anxiety after getting a Chihuahua puppy

Hi everyone,

Last Thursday 2/5, I received a 3 1/2 month old Chihuahua puppy. My current living situation is that I live alone with my 17.5 year old Chihuahua that I’ve had since he was a puppy so for 17.5 years it’s just been us. So we are extremely bonded even though he is now quite senile. Now we have a puppy in our family and it’s been one of the most stressful things I’ve been through in my 41 years of life. I have already lost 3 pounds. I feel deep regret. I feel like constantly entertaining a puppy is not what I want. Or listening to him cry all night and sleeping with anxiety meds and earplugs. I just want to go back to my calm peaceful life. I’m aka always concerned about disturbing my senior dog even tho he can’t really see or hear good at all and rides around in a stroller, I’m sure he senses the new pup… Everything I’ve read mostly says “it will get better” but I am in tears every day and have never in my life felt this bad. What do I do?? Do I give him back to the breeder or keep suffering my health and give it more time? I’m seriously concerned about my health and how this anxiety has affected me.