I had a huge separation, apparently it got to 9cm but I think it was honestly more like 7 or 8cm from what I could feel. The physio will give you exercises to do, but an important one is your pelvic floor. Mine went back to about 1-2cm by 9 months PP...unfortunately but that time I was pregnant again so it's all beginning again Things like making sure you roll to your side and then sit up before getting out of bed are important too.

ETA yes, that tent! Mine made a huge one and makes a small one now. That's your guts poking through the muscles :/