Sleep training

We loved co sleeping with our son and it was what worked best for our family but now he’s getting older so we would like him to have his own time and us the same. First night we tried CIO. I had to give in .. it was so painful to hear him scream and say mommy please . Mommy no . And calling for the dog . Just anyone . What did me in was the panic and fear you could hear in his voice .. how do I get past this . Any tips or suggestions on how to get him to sleep . I don’t mind patting or sitting with him but sometimes it doesn’t work