when to fight back

Never is the answer.

Why lower yourself by trying to make her life miserable? Ignore her. Don't take her calls. I don't get why just because someone hurts you, there is a need for revenge pain to be administered. You'll be happier just forgetting about her and moving on.

Oh, do the mature thing. Delete her contact info, get rid of anything she gave you and go out and have a good life, not thinking about her at all.

I appreciate your candour and in principle agree. I'm sensing a theme here.
However unfortunately I now work with her old colleagues, I live In shared accommodation where she used too. And she is insisting on coming back to after embarrassing herself. I would very much like her to leave and things to be the end of it. Unfortunately she seems rather insistent upon twisting the blade.

being mature is nice, turning the other cheek is nice, but Im running out of cheeks (and metaphors)

So what? Working with people she used to work with should be no big deal.

Again, so what? She no longer lives there, so how does living there create a problem? But, if it bothers you, find a new place to live.

Coming back to where or to what? I'm not following this. I can't imagine she was rehired, and the place you work probably would frown on her just showing up there regularly to talk to old colleagues.

None of what you seem to be complaining about is her trying to twist the blade into you. Unless I am missing something, I don't see why you are going crazy over this. Just look the other way and move on.

(See how easily I threw in another little saying there. I would hate for you to run out of them. lol)

haha, appreciate the response and the extra sayings.
unfortunately its quite a small remote village, there is no alternative accommodation, the guy she shacked up with owns one of the only places here to go out to for a social life, she is coming back to visit the projects we worked on and to go and stay in this place with this guy for who knows how long. I guess the act that she pulled over the holidays didn't work and I didn't take her back so shes shamelessly going for her other option. the guy she cheated on me with. unfortunately this is such a small place. I either have to like it ...or lump it...... or .......

now its the other option im looking for. because while I definitely do not like it (it hurts and is upsetting and pathetic).....I also don't feel very much like lumping it anymore. Though far more dramatic and oh so cliché, perhaps beating the **** out of the guy might make me feel a little better (he knew all about me and that I was coming out to work here....as such I believe him to be very deserving of at least an un-gentlemanly talking to)
or what else, well believe me, a number of things have come to mind and I guess this is me mulling over how much longer I am expected to lie down and take it.....or whether its just about time I stand up (as I said....oh so dramatic)

Awesome. Enjoy getting arrested for battery.

The extra info does clarify why you have limited options. But I don't think it changes my advice to just leave it all alone. Ignore her. Show her it doesn't bother you. This will probably be the best "revenge" you can get. She will realize you just don't care any longer.

Perfect answer CR

Count - you are going to have to be strong to rise above all this - since it is being shoved back into your face because of work circumstances.

Can you ask for a transfer at work? Surely your boss would understand if you told him about all this.

ALL of these people seem quite crazy and are not healthy for you to be around. Do whatever you have to get away from this work setting and from her and her minions.

This is going to make you crazy unless you can get away from this.

....how much abuse ......?

How much can you take?

here is the thing. he owed/owes you nothing. he wasn't in a relationship with you. blaming him is going to go nowhere. people in the community are going to think you're a dick for taking it out on him.

the person you have an issue with is her. she's the one who crapped out on your relationship. she was an asshole and it probably feels really awful to have been totally **** on by her.

so if you want to beat someone up, it's probably her and that's not going to be acceptable. understandable but not acceptable.

you can choose to deal with her directly and honestly, or avoid everything and everyone to do with her (tricky in a very small community but possible).

My approach would be to be very honest about it. If she approaches you, privately or in public, let her know what you think about her and how she treated you. The one possible joy for you in this approach is that you could make her very uncomfortable by simply being honest about the situation anytime you're asked about it. It's really the only consequence you can make her face. Incredible discomfort.

you don't need to be dramatic in your responses to her. just honest. coolly honest.