@Lacey2019 so sorry you're hurting like this.
Something that stood out to me, is when you said this - I have always prided myself on honesty - my love, something that will make you feel a lot better, is to look closely at this statement and think about why you've applied it to another person.
There is nothing wrong with being honest, it can be a virtue in many situations. But, and I meant this gently, it's not always the best thing to do, and it's not something to expect from anyone else.
That sounds really cynical and brutal I know - but what I mean is, many many many people are dishonest not because they want to lie to you - but because they aren't even honest with themselves. They literally do not know how to tell the truth because the truth makes them feel like a bad person. So they lie, dissimulate, avoid, change the subject, etc. etc. in order to keep themselves from feeling bad.
This guy probably wants to be a good guy in your memory, and in his own mind.
Is that useful to you? No. Is it kind? No, not at all. But it is a powerful motivator for many people. So powerful that they will lie, lie, lie every day, sometimes for decades, just to avoid the feeling of being the bad guy.
Part of growing and maturing in life is waking up to the (often terrifying) realisation that other folk are not like you. And it causes enormous pain to expect other people to be like you, or imagine they are. I did this with my exh and it led me to so much suffering! I really do see where you are coming from. Over and over again I would open my heart, be honest, take responsibility, etc. etc. and every time, he would just take that as my weakness, rather than my love. But I kept doing it, until I learned - he isn't like me.
The pain you're feeling today is your heart and mind struggling to avoid the truth that actually other people aren't trustworthy, that actually, you are much more vulnerable than you thought you were. It hurts a lot to think about that, but it actually hurts more to avoid accepting it.
He fucked you over for his own selfish reasons.
In future, people will try to fuck you over again, for their own reasons. It's a horrible thing. Allow yourself to hurt, but don't fall into the trap of going in circles trying to figure out why he isn't like you. He just isn't - that isn't your fault.