'Lodgers' moving back home

DD, SiL & 2 dgs moved in with me lock stock & barrel 12 weeks ago while having work carried out on their house which is a 10 minute walk away. All a bit of a tight squeeze, noisy & messy but we all got on fine and I was available most of the time for childcare etc. SiL worked from my dining table 2/3x a week which wasn't part of the agreement, but hey ho, I put up with it even though I didn't feel I had my space during that time. I knew that all this would soon end and was dreading being alone again even though I was looking forward to regaining my house. I went away on Saturday for the night and when I returned last night, they had gone, just like that... Their 'stuff' is still here and the place is a tip. DD will be here this afternoon to start taking it away.
After all this time with constant company, I am feeling bereft..they are so excited to be going home, rightly so, and I am so unhappy to be alone again. Apart from the sheep baaing in the field next door, the place is like a morgue. Since DH died I have hated being on my own. I just feel like howling. AIBU