I am so frustrated at having to explain to my partner that I'm cant do things because I'm in pain

You’re not going through anything that most of us here have had to deal with, and it is frustrating. A lot of people here to give you advice, but ultimately, you’re simply going to have to have a long sit down with your partner to explain in detail what you are going through, and what you can maybe expect to go through in coming years. And your partner is going to have to decide whether or not they feel they are willing stand by you through all of that. And you will need to be pretty clear in your expectations of your partner in that regard.