3 Answers

You will get over it when you get through it.  It took me about 15 months for my husband, and we were together for 17 years.   
It has taken me nearly a year to get over a friendship of only three years.  I'm still hurt.
It's different for everyone.
There are 5 stages of grief.  Check it out by using your search bar "5 stages of grief".
My main advice would be, don't pretend anything. Allow yourself what time you need to get over him and be able to have a new relationship with no looking back.   
If you can find diversions that put you in a new place and cause you to focus on something besides him, go for it.  Exercise helps, too.  
You have my all-too-sincere empathy. 

First of all, people handle different situations in different ways...kinda like the saying goes "different strokes for different folks". But I truly believe, if you are truly over him and have a another man in your life you have moved on, it's time to let it go, period! If you're not really over him, then this other man doesn't have a chance. You have to make up your mind either way. If you want him back than go get him, otherwise girl move on and don't let him rent space in your head. You are doing the right thing talking about it, asking questions! But what ever you do, do something about it! I was told a long time ago, that thing between my ears should only be used for recreation only, left to my demise (that stinkin' thinking) I'm in trouble! I don't know your true situation or why you split in the first place, so all I can do is speculate on your situation. I hope I helped in some kinda way, take care.