You can do it, honest!
I am one of those single parents of a 7 month old (thanks for the hat tip!) and some things I'd suggest are:
Coming up with a scheme for where to put the baby down safely is key - I'm sure you already have this to a large extent, but you may need to extend it a bit to cover activities where previously your husband would have had the baby while you did them. So, for example, when I take a shower, I take the baby in his bouncy chair into the bathroom with me. Generally, just plan on carting the baby about to hang out while you do stuff.
I definitely had a few tasks that took some figuring out. If your husband hasn't left yet, crack on and practice the things you aren't sure how to do, so you can figure them out ahead of time. If he has, not to worry, you'll manage!
Simplify, simplify, simplify. Does a task really need to be done? Really really? Ironing, for example, doesn't. Ditch it for now. Drop your domestic standards a bit while you get to grips with everything. Focus on loved, fed and clean.
Make extra portions and freeze or refrigerate them, to minimise how often you need to cook. Also, figure out stuff you can make really fast (hello, pasta with pesto and some broccoli). For a couple of months my 'fridge salad bar' (make one new thing a day in rotation, takes like ten minutes) saved me!
Get everything ready ahead of time before you start key baby-related things (like a bath, or a meal) - there isn't someone else who can pop to the bathroom and grab a flannel, or whatever. Have it all set up like a surgeon!
If you have a baby who will sleep in his cot/nap not on you, hurrah! Get stuff done while he's asleep. But even if you don't (waves!) you'll still be able to get done the things you need to do. Remember, this stuff is just as interesting and stimulating to babies as 'an activity', because they're babies and everything is new.
Basically, all this is just stuff everyone does with a baby, and I'm sure you already do, too - it's just dialled up a bit. You can absolutely do this - go mama!