My son's off to residential college in September - looking for information on how other parents cope

Hi joined this community as feeling the strain a little. I am Mum to 2 lovely boys and I work full time. Our eldest, 19, is off to Residential College in September after a long, fraught battle to get him there. He's going to be there 5 days a week with us picking up/dropping off every weekend. I'm ecstatic that he's going but now the worry is setting in...also what do I do every night now? My whole life has/does revolve around him and his care, hospital appointments and his social life. I expect the 15 year old will find life very strange too as he is the carer from 4-6 every evening til I get home from work!  Just wondered how other parents cope really.