I get those ADCs sometimes.
Mute them, if theyre just flaming... ignore it and you will probably have a decent game. If they start acting out like griefing, typing a novel and missing CS, or abandoning the lane leaving you there alone... just roam as best you can. Cause if youre lucky they will calm down and farm and contribute. The other thing that could happen is they could shit the bed even harder than when you were there and you can make some great roaming plays and everyone will know who the problem was and report them maybe.
More often that when an ADC starts in on me I say "sure, blame the support." If the persist ask "should I mute you now?" If they go for strike three, dont say anything just mute them... they will run out of steam typing at you after a while with no response... Honestly, you dont have to mute them, just ignore them. They may say something useful... maybe. Just dont respond to them, and if its anything other than flaming or rage/salt take note, otherwise ignore.
If you feel like gambling, at the first sign of flaming ADC syndrome try saying "Oh I love rage novels in the chat, go for it man, type away." This will either make them NOT type cause they dont want to give you what you asked for, maybe even make them see the trap and not walk into it, or have them give you what you asked for and they start raging out of their minds.
Good luck, playing support can be very rewarding but part of the price to pay is having to endure some of the worst players in the game blaming you for everything they do. Try to stick it out if you can, but if you have to roam, it will be up to you to judge when to call it quits on bot lane and when to stay.