Cheating - I keep pulling what I know apart and try to put it back together again

[nowaybaby]

These are the facts. Please tell me what you think.

Your partner (caring, committed, good company, long term relationship) gets a text from another woman. It says 'I need to see you.'
He tells you that it is woman he met for coffee once, at least 4.5 years ago.

You ask why she wants to see him. He says he doesn't know. He says he has been 'helping her because she is in an abusive relationship'.
You ask to see their messages. He has deleted them. He calls her a nutter and says he doesn't want anything to do with her.
He lies about where they met because the place he names didn't open until over 2 years after they apparently met.
The OW is married with a husband who works abroad for long periods.
You contact the OW and she says there is no relationship. However she says they met for coffee twice and says he had been single for a couple of years, when you know that your relationship started after he was single for one year.
Most importantly she refuses to say how they met or even which year. She says she can't remember and it wasn't important to her. She says she didn't mean to send him that message, it was for someone else, although when it happened that's not the way he acted. No apology offered for upset caused.

He swears he has not seen anyone else and also swears he would never cheat because he knows what it feels like. The relationship is over because he says he knows I don't trust him now. But I'm left feeling like the crazy one because they both know the truth and I don't.

I've posted about this already and had good advice. But I'm struggling. Please give it to me honestly and help me come to terms with what I thought I knew about him and our relationship and this new information.

Did he tell you he was infertile as a reason not to wear a condom?

He calls her a nutter and says he doesn't want anything to do with her.

This statement above was the biggest red flag to me. How many women do you know - objectively - who are "nutters"? For that matter how many people of any gender do you know who are "nutters"?

This is a classic male move. If he's telling you that another woman ( either a perfect normal non-nut case or a woman who is appropriately upset at being treated like an emotional doormat) is a nutter this is not a good sign (unless she's , you know, boiled a bunny and murdered her children).It also means he's probably tell her you are a nutter. I mean why wouldn't t he. It's how he manages people - by divisive, destablising lies.

Unless you are in the exceptional situation where there is real evidence of mental instabilty (Beyond normal emotional "relationship" upset), this is the most telling example that he is shagging her.

To you: Nutter. Stalker. Obsessed with me. Never gave her encouragement. (Meaning I;m enjoying sex with her and I'm trying to have my cake and eat it for as long as I can manage).

To her: Psycho. Told her its over but she won't let go. Think she's a suicide risk. Will leave her soon/when it's calmed down/next year. (meaning I'm not leaving until she dumps me but please keep having sex with me).

BubblingUp - to be fair, I think he believed this after a HCP told him he would not have more children. He has taken responsibility for this. But it was one of the worst situations I have found myself in and he left me to cope with miscarrying alone.

ZBWRDSM - thank you, you have articulated this situation well. It is really disrespectful to her, after being disrespectful to me. Of course, in RL I think he wanted to steer me clear of her in case she told me something incriminating. When I said I might contact her he said 'she won't respond or she will say all sorts because she likes to stir things.' Covering his tracks there, I think.

Liars have to keep covering their tracks and often their victims are manipulted into feeling guilty so go along with it.

You need a good break to really let the truth sink in and the lies will be even more obvious.

My STBXH only tells me the truth when it works in his favour or if I get him angry and he blurts it out before he can think of his next lie. It's very hard to talk about access with DCs when he isn't straight. Our eldest really doesn't trust him.