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i recently found out from my step mum (she divorced my dad but we're still close) that while she was dropping off my younger brother to go stay with my dad he was being overly friendly with the new girl at a local pub, he introduced the girl to my step mum and while she was still there, my dad and this girl were all flirty, touchy, kissy and basically just all over each other, you're probably wondering "hes a grown man he can flirt with whoever he wants" or "whats so bad about that?" and before i answer that im going to give a key bit of information as to why im so grossed/freaked out. im currently 17 but im turning 18 in basically 4 months, my dads 48. the girl he's getting handsy with is 18, wether she turned 18 this year or is turning 19 before the year ends doesnt really make a difference. i dont really know what to do in this situation and on top of that, hes still hooking up with one of his housemates which is the same age as his mum. so not only is my dad potentially shagging a girl my age, hes also messing around with a woman the same age as his mum. he doesnt know that i know but i have to go visit him in like 2/3 weeks and i have a feeling hes going to subtly introduce her as his 'friend' as hes done in the past. any advice for how to go about this?