Can I get sepsis from a perianal abscess? I have a lot drainage and have felt ill all weekend, I had it lanced 5mo ago. Can I wait til tomrw to go in?

Yes. Perianal abscesses can cause severe sepsis if not treated properly with drainage and antibiotics if there is associated cellulitis. You are draining but it may not be adequate if you are feeling ill. A recurrence as you are having is not uncommon and must be taken seriously. I suggest going to the er to get examined today before you potentially get worse.
Maybe. If you have no fever, and you can tolerate sitting in a chair, you can probably manage till tomorrow. But you probably should make sure somebody examines you tomorrow.