my managers expectation are very high as "Team Lead"
Promotions come with increased expectations - sometimes massively so. With great power and all that.
It's an unfortunate reality of human nature that first impressions matter, and it would appear that your first impression on the your manager as a new Team Lead..wasn't great. Add in that if your manager was one of the people who made the call to promote you then your mistakes also reflect on them as well.
To be honest your "mistake" wasn't that big a deal in my view - yeah you were out on an estimate by a significant margin but if you're going to be out by such a margin it's far, far better that it's an over estimate than the other way around. Honestly if you'd done the same thing in 6 months time it wouldn't have been anywhere near as big a "thing"
How to handle project manager who is always on fire now?
Unfortunately in the absence of a working time machine you can't go back and undo that - so the best thing to do going forward is to be whiter-than-white. Then if after a few weeks of you getting things (particularly estimations) spot-on (well, at least within closer margins - anyone expecting an estimation to be 100% accurate doesn't understand what the word means!) if they are still giving you a hard time over the previous mistake it would be fair to say
I realize I made a mistake in one of my first estimations but I think I've shown over the last X weeks that it really was a just a blip and that I'm capable of estimating well so can we move on from what is in the past please?
I am loosing my interest of work due to this issue ?
I don't say this to judge but if you're starting to give up this quickly are you sure you want to be in a leadership/managerial role? Like I say it's no judgement on you if you don't, it's not a case of being "better" or "worse" it's a matter of whether it's suited to you and what's going to give you the best work life for you.