Do I tell him it's over?

[Inamusical]

After 2 years of problems and me asking for change, DH half heartedly trying and then going back to previous behaviours, I've decided that I want to separate.

Due to a number of issues, lack of finances due to the impact of covid and me not earning enough independently, along with several other important factors, I envision that the separation won't actually happen for another 18 months.

I believe that DH has been actively, but subconsciously sabotaging our happiness and he has a lot of issues to work through. It's taken me a long time to realise that I'm not his psychologist and that it's time for me to get my life on track.

At the moment, we are living together very amicably and we are still able to enjoy family days out with our children together. There is just no romantic relationship. On the whole, DH goes without any intimate connection quite happily, but maybe once a month, he wants a romantic relationship for an evening and then continues his own life again.

If I tell him my plans, I'm concerned that he may become angry or even desperate and start behaving passive aggressively again. He has only once let his temper show openly and I can see, that when things don't go his way, there's an angry man simmering away. I don't think he'd intentionally hurt me and I'm not scared of him, but there's a part of me that worries how "tactful" he might become should I be open and honest with him. I expect he will start squirreling money and that he'll enlist his parents in helping him seek legal advice regarding the children. He has much more support and financial backing than I do and his Mother will no doubt want him to push for 50/50 custody which is not what I want at all. He will also create a miserable, tense atmosphere at home, sulking and being obstructive which isn't good at all for the children.

Despite all of this, I'm not sure how easily I'll be able to "appear" compliant for a whole 18 months. Part of me also thinks I ought to be open with him.

Do I tell him or not?

OP, I didn't want to read and run. You say he's only once let his temper show openly, but there's an angry man simmering away. Yes, I think he will be extremely resentful of your assertiveness once you have told him your plans, and unpredictable in future behaviour, especially if you have to live with him in the meantime. It doesn't sound as if your MIL is on your side either, which could add up to a toxic mix, and you have to live there still.
I had a 2 year plan to leave, but lasted 18 months before the argument which confirmed the end of the relationship, we are not married, but have to live as housemates now until the house sells, and, like you, I am nowhere near financially prepared. I do not have a job to go back to after the Pandemic, which has changed everything.
Please help yourself by stashing documents for you and the children like birth certificates, and see if you can sneak copies of his payslips, pension etc, which would help with a final settlement. As his wife, you are entitled to half of everything, but if he sqirrels money away, etc, you need to be prepared.
Please read the recent thread on the Relationships board, "Made my plans to leave next week but am so scared" it had useful tips for anyone in the same or similar situation. I'm pleased to say that the Op on this thread made her escape on Wed 30th Sept eve, and she is in her new home.
Sending best wishes

Thank you @carreterra
Hope things work out for you soon and well done for going ahead with separation despite all of your uncertainties. I wish I was brave enough.

I wouldn't tell him, if you're not ready to make any moves for another 18 months. Although I would stop having sex if you still are, unless that's enjoyable.

I'd get things lined up on the quiet and tell him closer to when you can actually separate.

No, I wouldn't tell him. Not until you have everything lined up and are ready to go

I feel more comfortable with not telling him I think, the more I think about it. I think continuing more with separate lives would be a good idea as not to lead him on at all. Sex is quite rare anyway- perhaps once every 8 weeks, but stopping entirely would probably be a good idea. He will get suspicious, I'm sure as I have the higher sex drive and don't usually say no.