Is there any chance of telling them together? I think both these ages are a bit too soon to delve into alternative attractions. What they need to know is that they still have parents who love them. They will wonder about things like if they will still go to the same school, see their friends, where will they live? Maybe they will ask why it can't be fixed? You need a gentle way to tell them that you and their mom are not compatible anymore but respect each other enough to be co-parents. I'm sure others here have faced this with kids of similar ages. Hang tight for responses, these last few days before Christmas are usually busy for most.

I'm in minority here..I do not think such young kids care why you're separating. TGT is hard for adults we tell to understand ..not sure if the kids want to be burdened with that.   They just want a mom and a dad. 

My kids are doing good. I just try to be the same dad they always know and can come to with any problem..they love their mom and I won't interfere with that..but they know they can talk to me when they need empathy and calmness. 

Our kids get all the rights and privileges of our time, talents, and fierce love.  Our gay spouses/exspouses have forfeited their rights and privelages. 
Ie.  Kid text me = instantaneous reply from dad.  Absolute reliability.  GX text me = delayed reply when I feel like it...none at all if its non urgent.

JenS. + 1.   Unfortunately it is a marathon !  Also you will feel different over time.  That’s a good thing !!