I don't know much about Montreal, and I've never been alone for 2 weeks... but I actually think I would REALLY like it.
The only thing comparable is the time I had to do my own thing in a new city all by myself. DH was at a convention and I tagged along to LA. We knew friends there, so I wasn't by myself all day every day, but I was alone half the day at times... and I was determined to not just sit in the hotel room and sleep (although I did do that the first day just to get it out of my system). Like you, I researched some places I could visit. I took my time walking and exploring at my own pace.
But I will say... it did get lonely. And I wasn't alone for as long as you will be. I am an extrovert, though. I NEED people-contact. So, I went to Starbucks 3x a day and sat among others. It made me feel better.
Another thing you might consider is to take some sort of class. Join some kind of volunteer effort in Montreal. Some way to make contact with people, perhaps meet some friends. If I was husband-less and child-less and fancy free for 2 weeks I would immerse myself in some project. Like, an oil painting class or pottery. Or, take horse back riding lessons. Maybe plan out a photography & journaling project...
Just a couple ideas.