Just need some help

Hi sorry for a bad title but I'm struggling, me and my partner have been together for 17+ years 3 children. The last 2 weeks she has been more distant than ever in this time I was going to work and saw a message and yes I could have ignored but I didn't and saw messages between her and her friend saying how much she likes this guy and it excites them, with the friend who I never speak to say get rid of me. I approached her about this but All I got is that it's only talk and nothing has happened but loves me but not in love with me and she has been like this a while.

This has happened twice before but I really thought it would have been different. I asked her why she couldn't talk to me as apparently she is my best friend but there was no answer to this. I asked why talk to her friend about it and they just said because and that they hate me ( don't know why but this really hurts too )I asked why but it's obvious if you never say anything about good traits I'd always look bad if it's always moaning.

I'll be honest me and my partner have had a tough few years but she is and has been very unwell with her thyroid and now weighs about 7 stone, every day during these years I've been more of a home carer (when she is not working and she does work hard) as she is always tired which is understandable so I will do the cooking, bits of shopping, put the kids to bed, meet her if her bags to heavy, hold her hand if her hands have gone white (Reynard's). My partner (or ex 100%) didn't do anything to help her illness and that was not all on her the NHS is a mess and her consultant doesn't do anything (no answer to a blood test in 3/4 year) but she never chases anything even though I try to push her to as I'm so scared she will end up dying.

I told her that as it is my mortgage and I pay all the bills including her mobile that if she doesn't want to work on it and maybe some counselling then she only has one option and that is she needs to leave me, she suggested cohabitation but after less that 12 hours of kind agreeing that it was to painful for me and I'd only make her hate me more as I'd be on constant hope. She said she understands and the children will stay with me until she is not in a friends spare room (zero savings I've told her she has 100%access to the children day or night and would hope that she can keep talking to me (I've noticed it's already only are the kids ok messages when she is not in the house)

She is a great mum who loves our children very much and I think cares for me. I would never stand in her way of happiness but at the same time I love her so much, we are having the talk with the children thing tonight where I have told her she needs to be honest that mummy doesn't love daddy like she used to which she says she agrees with.

I'm just so scared I'm giving in with trying to see her happy, as she has told me she has had depression in the past and lied to the GP and with all she is going through with her thyroid.

I know there will be no right answer to any of this but she is my world at the same time and don't want our children to say next week or year or ten years you should have done more dad to fight for her.

Id love anyone's opinion as talking really helps me and my partner/ex isn't that type of person.

Sorry for the all of text and Mish mash of paragraphs was just talking with my fingers.