This is a hard step to take Tom..  Sorry you have to start thinking about these things.   But I think you are very wise to be researching these things now. 

The first thing I would do is research your state's laws on separation and divorce.  Some states require a legal separation for a period of time before you can petition to divorce.  I know you don't want divorce at this stage, but if you are going to do a separation, it might makes sense to have it follow your state laws in case you do decide to go for divorce later on.  For example.. You might consider being separated, but still living in the same house.. You might do that for a year and then both decide for divorce.  But you might find that the state requires a separation to include living in different homes.  If that were the case you'd have to move apart for another year before the divorce.  This is all hypothetical of course because I don't know what state you live in, what the laws of that state are, and I'm certainly not an attorney..   But you might want to look into this.  

I would also start researching your state laws on parenting time and financial support.  I know this isn't divorce at this time, but it seems like having this knowledge ahead of time is smart.  If you put agreements in place for a trial separation, they might carry weight as a precedent when it comes time to go to court for divorce.  If you agree to higher or lower spousal support and/or child support during separation, perhaps the court might lean toward continuing that agreement in the official divorce??   Again, i'm not qualified to give you professional advice, but it seems like you would be wise to create your separation agreement in a way that reflects what you would want your divorce agreement to be.. this should make it easier when it comes time for the divorce..   Again, I know you don't want divorce, but it would be prudent to plan for the worst at this stage. 

I can't share a ton of personal experience in this because I didn't really "separate".  My ex just filed for divorce.. there was no trial period or separation phase for me.   But perhaps a few things might help.. 
During my divorce period (6 months), we separated emotionally and physically by having her move to a different bedroom in the house.  She must have been advised by a friend that she should not move out of the house.  I got the same advice from the internet and an initial attorney consultation.  Turns out, if you move out of the house without a legally approved separation agreement, you are deemed to have "abandoned" your home and family.. doing this will hurt you very much in court.   So, strategically thinking, if you can get your wife to move out without an agreement in place, that would help you in the future. 
- I made the mistake of assuming that the woman always gets preference in parenting time... So I assumed I'd be an every-other weekend dad and had to negotiate back up to 50% from there.   If I had started the conversation differently.. with the idea that she was the one breaking up the family and abandoning us and that I should get primary custody.. then she would have had to negotiate.. it would have put me in a better standing.   I would recommend assuming you will get primary custody and force her to try to negotiate it back.  Be in a position of power from the start on this case. 
- Child support is typically a formula determined by comparing the income of each spouse.  The idea is to normalize the cost of raising the kids based on the income ability and the amount of time spent at each house.  So this is usually not a point of negotiation.. it's more like you are just told that you will accept what the state calculates.   You might search the internet for a child support formula calculator for your state.. I did that and it was pretty darn close. 
- Spousal support or alimony is something that is usually negotiated between the parties.. unless they can't agree and then the judge uses some formula and makes the call.  The idea is to normalize the quality of life for both parties given the fact that often one spouse is the primary income and the other is the primary care-taker.  However its not meant to give a permanent income stream (usually).   There is an expectation that each adult will find a way to earn an income to sustain themselves, so there is often a time period for spousal support that allows for the one who hasn't been working to retrain or get further education, etc..  

With all of this, I would strongly recommend talking to an attorney.  You can usually get a free or low-cost consultation.  You don't have to file for divorce.. you are just there for an education.  But it's important to get a good education because the terms and legality of separation can influence the divorce process if it comes to that. 


Hopefully some others offer more personal experience on the actual separation..   

Best of luck to you!

I think you have been given great advice.  Don’t leave the house and assume you are entitled to at 50% and negotiate from that standpoint.  The best outcome would be for her to move out because you need space to get your head in a better place.  It takes sone time but eventually you start to see things as ‘you’ instead of ‘we’ and it’s important step.

Good luck !