How long is it normal to grieve after a breakup especially one that lasted a little over 8 years?

I'm still in love with my ex, he broke up with me almost 5 weeks ago because he just felt he wasn't in love with me anymore. I cry everyday and try hard to only do it when our children are not around but somethings make it hard like when my 5 year old said this morning that he missed his dad and he wishes we were all together again. Everytime I feel this baby move it's just a reminder that we planned this baby together and he wants nothing to do with me anymore.