I have to say that, from what you have told us, I share @empirebiscuits12view that he is a nasty piece of work - though I am equally sure that isn't all he is, and that the things you perhaps still like/love about him may well be real too - people are complex, after all.
To me, his maintenance of the harem, at the same time as talking about a future with you (future-faking? Though it's possible he was entirely serious) implies he is a selfish man, and somewhat manipulative perhaps, as he arranges things around him to suit himself, nobody else.
If he IS involved with the landlady (which seems possible from what you have said) then he was exploiting both of you - very cruel to you, as a clearly lovely, intelligent, good hearted woman who saw the best in him - and also quite cruel to her, as one assumes it was painful to her, if she does have feelings for him, to have to witness at close quarters his burgeoning relationship with you. (Though I also think she herself behaved badly if this is true, no question of that).
I think negging is vile, childish and pathetic, and I think he was guilty of that.
And also I think his behaviour shows some hallmarks of lining you up for possible financial exploitation. And that's something I utterly despise - when a feckless man finds a woman who has worked hard all her life, and sets his mind to helping himself to her hard earned financial security. (Perhaps I feel so strongly about this because I have been the victim of it myself, more than once).
None of this is to say that I don't believe he can also have good points - and indeed when he said he loved you that may well have been true - I think even cocklodgers tend to pick women they admire/are attracted to/love - as it would take a pretty desperate person to tie themselves for life to someone they have no feelings for. It's always a bit more complex than that.
But on balance, you deserve much better. And I think you have set a brilliant example to us all by having the strength and self worth to walk away, despite your strong feelings for him....
So he kind to yourself, please. You must be feeling so many conflicting emotions right now, and I imagine every day it's a struggle not to text him. But I think you need to still think on terms of a day at a time. Dating others is probably a good distraction, but don't put any pressure on yourself to meet "the one" right now - just enjoy the dates for what they are.
And you just never know. I was PAINFULLY in love with my negging narc ex (who for ease, as I reference him on here a lot, I will call Mr Tortoise) when I went on my first ever OLD with my more recent ex (who is now my FWB). And even though FWB hasn't turned out to be my happy ever after as I hoped, he is 800000x the guy Tortoise was, and happened when I was least expecting him.....
I think that's why I retain hope, actually. Sometimes you can meet someone and you just know. And maybe it lasts a couple of months, a cpuple of years, OR a lifetime in some lucky cases.
But it's worth 20 or 200 dud dates I think, that vertiginous feeling.....