Agree with May - this will be a repeat of your past attempts unless you do something different.
What you had before was not a separation, so that's a start. You said you wanted space, but that was not really defined and it was a boundary that was not held. So in that sense, she hears words but does not expect you to follow through. It was you half-heartedly trying to push her away but not really doing so fully.
You say you don't want a Divorce, and I hear that. But you also don't have a marriage. I think you really need to reflect on this piece. I'm not saying you need to file now, but I do think you need to identify what a Separation really is. It means you don't have one another in your life, and you'll be living very differently.
This isn't a separation where you just want space or time - you have to very firmly state with your actions that you do not want her and that any approach will be met with your back turned.
Perhaps this time it is different with your delivery. In the past you've tried talking, giving letters, explaining, sharing your feelings. She is not entitled to those any more - she knows how you feel. You can walk away and feel confident she knows how you feel. Do not think that if you only told her "one more time" anything would change.
Perhaps this time it is fewer words. Simply, "I'm done. Do not reach out.". Really - less is more. And then stand firm to it. No need for anything elaborate, and it may be easier for you if you simply stick to a few words.
I think practicing here or talking about your plan as you lead up to it may make you feel more confident, which is key. Sticking to this is going to be very difficult for you, and we're here to support you in it. But I do think that after several weeks of a new routine you'll start to feel different, and it will set you on a new path. You don't want to keep living this limbo world for the next year with someone who can't take a step towards you.
