Indeed, isolation is a huge part of codependency. Like you, we feel embarrassed and ashamed, and since there is nothing good going on in our life, we have nothing to say to them that they would understand. And we're so exhausted from looking after business at home, we have no energy to do anything anyway.
I am so glad your friends spotted you, that seems to have been the push you need to get back out there among family and friends.
I was surprised and delighted to find that my friends still loved me, even after I had treated them badly through neglect, and my family stood by me no matter what.
Something that helped me was to go to meetings. That got me "out" yet I was surrounded by supportive people who understood me. Often I would go for coffee after the meeting and begin to feel like "normal" people having coffee and fun.
Thanks for posting this, I think it's an important topic to talk about.
Hugs