https://pcpartpicker.com/list/ngkTGf
click [edit this part list] and click the motherboard section.
it'll show compatible ones with the i7 8700k cpu.
also same with ram (after u pick motherboard and click the ram it'll list compatible ones for it)
if you plan to overclock the 8700k i think you need a Z type board like z370 and z390. the b and h series ones do not allow OCing (iirc)
also k series do not come with heatsinks and need purchased separately.
and finally if you are regretting it and are able to return/refund it should do so as last thing you want to do is regret something after spending much $ on it.
(personally i like intel but amd isnt bad just personal pref)