25weeks husband leaving me..help...

Hi all.. im 25 weeks pregnant and my husband has decided he's had enough and is leaving me.. we have a 5yr old boy already.its breaking my heart.. dont blame him if he's not happy dont want him to stay just because im pregnant.. he's staying in our home but sleeping upstairs which is nearly harder for me.. I'm devastated and cant get my head around it.. Cant have a breakdown as my son needs me and iv a baby on the way.. Can anyone give me advice to get through this alone :(