WAW with a twist, she's asked me to move out!

[Istherehopeforme]

Hello. New to this site and this sitch.
Married for 15 yrs. W is a ACOA M.
S10 and D20 (from her 1st M - I adopted her when she was 16). D20 moved out of house almost a year ago.
Out of the blue on July 20 she askd me for S and for me to move out! Her reasoning was that since I travel a lot for business our son is used to having me not be around so much. She says she's not been happy for a couple of years.
Mid-Oct after veiled threat of D I finally moved out to a condo we own about 40 mins away nr beach where I am still living. Its very lonely and inconvenient.
We're still mostly cordial and try to keep things pleasant. We even do "nesting arrangements" where I come to stay at the house with S10. She often stays with a friend or sometimes is there as well (different Bdrm).
At end of this month a rental apart which we own becomes avail, 1 mile away from our house. I suggested to W that she considers moving into it and I move back to house as this would afford her the complete separation, ability to lead a discrete life if she wants. She could then stay in the house when I travel for business. She declined this offer for the sake of S10.
The question I am wrestling with is whether to make an ultimatum. If she wants separation then move into the condo down the street or I'll move back in and take the spare Bdrm. I've been to see a C about 10 times so far. She is going to see one for 1st time today. Right now I'm getting ILYBNILWY but she still wants to be friends and to have me in her life. She is making effort to go out with new friends (ones who I don't know). Said she has a "date" tomorrow night.
Here is my dilemma - do I give her an ultimatum? If you want S then you move into our 1 BR APT 1 mile down road and I'll move back in to house. She would still come to stay at house when I am traveling. Besides the probable degradation on pleasant relations w/W my worry is that this arrangement may be more disruptive for S10 - he is definitely closer w/W than me.
Otherwise plan is for me to move into the 1BR 1 mile away.
Trying to reach out for unbiased opinions.
Thank you in advance for taking time to read and respond.

Istherehopeforme