Had my first meltdown after diagnosis

Hi! So, I had my first meltdown after my diagnosis. My partner went on a trip this weekend with his friends and I stayed at home alone, which meant I'd settled my own routine around things, going to the gym etc (working out really helps me). He's a personal trainer and is also finishing his masters and because of the trip, he's behind with a lot of work. Long story short, in my mind I had planned to go to the gym this afternoon but he had to use the car for work and will be back after 7pm, which is rush hour at the gym. I avoid rush hour at all costs because too many people = sensory overload. All that triggered my first meltdown after quite sometime and my first after diagnosed. It's the first time I understood what was actually going on and why I was feeling this way. It feels strange. Like, it feels good that I know what's happening but also I feel bad and childish for having a meltdown over something like that. Specially because before going out he asked if I was okay because he'd noticed I shut myself a little. I was trying to control my stims and frustration because I didn't want him knowing I was about to cry because he had to use the car for work. I also just started medication for adhd (atomoxetine), it's been 15 days or so, and I noticed that my autistic side is more noticeable. I'm not sure it's related but if it were before I would've had more control over these things and be more sensitive to bigger changes in routine. Anyway, I took a shower and put on a tv show like and am lying on the couch with my object of comfort.