Not coping well...

I go for my methotrexate shot tomorrow. I have a PUL and will be 6 weeks 6 days. I’m really scared the shot won’t work. This entire experience has been traumatic. I feel like a ticking time bomb waiting for a rupture. I had been TTC my first for 7 months and this has been the worst experience of my adult life. How do I stay calm waiting for my numbers to go down to 0? It can take weeks and weeks. I just don’t know how to stay strong right now.