Yay!!!! you're back, you've been missed!!
I am so very sorry to hear about your arthritis. But there are plenty of things that you CAN do. At a gym they are probably very experienced at this type of thing and will be able to guide you in the right direction. If not there are plenty of other resources to find out some information as to what kind of exercises that you can do. Hang in there. You will find something.
You are certainly NOT a failure. Failure is giving up totally and here you are back on plan for 2 whole days already. That's a great start. And don't you know we'll take you here no matter what, through the success and the struggles. That's probably when you'd benefit the most. You can do this, it might be a little more difficult, but then it will also be that much more rewarding. I'm glad you're back. You absolutely, positively, without a doubt CAN do this.