I'm so sorry.
No matter how hard it is though, do not beg him to come back, maintain your dignity.
Are the tablets ADs? If so they can take a few weeks to start working and the tears will reduce.
Do you have family, close friends who you can lean on? If you feel like texting, emailing, phoning him, then can you call a friend? My friends took it in turns to sit with me most nights. Sometimes they just sat there hugging me.
How old are your DCs?
Try to focus on you and your DCs, I know how hard it is but it is them that will help you get through.
Sleep when you can, even just naps. Eat little bits, I lived on soup and bananas for weeks. Cry as much as you need to, you will start to cry a little less each day until you suddenly realise that you haven't cried for a day, then two....
There is a Paul McKenna book that may help, 'I can Mend your Broken Heart'. I haven't read the book but the CD that comes with it is very good and helps me relax, a lot of women on here recommend it.