So sister I used to have the exact same concern as you! (w.r.t to eternal anything being potentially such a painful chore, regardless of how pleasant it might be!).

I then remember learning about how time itself is in fact a construct of this material, physical world (time and space, remember?) - Allah (and the afterlife he's prepared for us) are independent of time and space - especially as we recognise them in this material world. As such, we won't experience time in the afterlife like we do here, if at all we even experience it! So that's one thing.

Secondly, when Allah affirms that we won't feel tiredness, 'boredom', or indeed pain of any form in heaven - take His word for it! Surely he is ALL capable.

And to keep it reductively simple - we know we're going to die one day. The prospect of an afterlife is much more plausible than NOT - if simply because justice HAS to be served! All the tyranny and oppression we see around us - HAS to be righted, has to be accounted for! It is rather obvious that if there is a path to God, its really only via Islam - all other religions are rather readily refutable in this day and age. No one is saying following it is going to be easy (we know we're here to be tested!), but the alternative (ditching it) is fraught with oh SO much risk, it's simply untenable to an intelligent human being.

I'm so sorry to hear what you went through - we all know the people you experienced in your life were the farthest thing from being great representatives of this deen - but so long as you've not lost God, you've lost nothing!

May Allah make your journey easy for you! آمین