Of course it’s upsetting and can be incredibly hurtful when a loved one lies to you and flings blame around rather than looking to themselves, so you do have to challenge them about what they are doing, but try not to get personal with insults or be very defensive.
It’s very hard but do your best to be supportive and calm, and be someone that the addict in your life feels they can talk to and open up with. You have more chance of them telling you that they have a problem and asking for your help to do something about it, if you can offer support and a listening ear.