Higgins, YES I know what you mean.  After being ignored for weeks, I found out that my xDSO was sleeping with a married man.  I gathered all her things and put them in a box and dumped it on her front porch. 

All of sudden, I get a flood of text messages from her, which was astounding because she had not been responding to mine the previous 4 weeks.  Her texts ranged from bizarre to just plain dumb.  I think in her demented head she thought that we could still be best friends while she slept with this married guy.  It was unreal. 

I ignored all of her attempts to contact me, but she still didn't get it.  So, to make things absolutely clear and get some closure for myself, I sent her a 4 page handwritten letter explaining how good I was to her, how much she had hurt me, and ended the letter by politely informing her to go F%$& herself and that the letter was the last time she would ever hear from me.  Ever.  This was about 6 months ago and I haven't heard from her since, so I assume she fully read and understood my letter.

Higgins it is ok to be selfish in your scenario.  Only do what is best for you until you are fully healed and out of the fallout.  Getting yourself back to a healthy and happy life is now your #1 priority.  Do what you need to make this happen.