Please hang in there. You have may it through the toughest hurdle...the separation.
If you don't want to have to continually change your phone numbers, try just not answering the phone. I know that sounds simplistic, but with our technological advances came another addiction for us to deal with...the phone. With cell phones everyone is so conditioned to be readily available that we have somehow forgotten we have a choice...to not pick up the phone.
As an extreme enabler, I know how hard this can be. It took me a long time to learn to do it, but it's amazing the strides it will make in ridding yourself of the chains of the addict. The addiction is like a leach...it is going to attach to something (someone) it can drain the life out of. If you are not readily available it is amazing how quickly the addiction will move on to something (someone) that is.
It sounds like you have a cell phone and a land line. Unplug that answering machine (just pretend it's broken) and, if necessary, turn off the ringer on your cell phone. You can always check it periodically to be sure no one else is trying to reach you.
Have your reasons in place for why you weren't available, in case you're confronted later. I'm not a proponent of lying as a general rule, but enablers have to protect themselves at all costs, especially in the early stages of ending a relationship.
Don't beat yourself up for what you've done to this point. It's in the past. Put it there and leave it there. What will get you through this is having the attitude that you're starting a new life. All that past stuff doesn't fit into this new life, so forget about it. You'll have plenty of time to think about it in the future in order to not make the same mistakes again. But for now, make it the past...you're not that person any more. You are a new person.
Again...please hang in there. I know how hard it is. I just had to separate myself from my daughter's addiction. I finally saw (after literally years) that if I didn't, she would continue and kill herself. I had to force her to be responsible for herself for once in her life. You can do it. I know you can.