This question does sort of cross over into parenting issues, although there is a clear interpersonal aspect of how to approach your wife.
First of all, you need to figure out what you actually need to talk about. Regarding the parenting, you mention that she may blame you for your child needing attention during the night in the first place. This suggests that she believes your child shouldn't need attention during the night, and that you ought to be using some method like "controlled crying" to get him into a routine of sleeping through. This isn't the right site to discuss the pros and cons of that, but certainly both parents need to be following the same "parenting style", because whatever approach you choose as a couple will only work if you are both consistent in your approach.
The other thing you should think about before you approach any discussion is how your wife may view a "fair" share of parenting. Who looks after your son during the day? She may hold the view that if she cares for him during the day while you work, for example, that you should look after him during the night. Of course, if you are working or otherwise occupied during the day then the alternative view is that you need to sleep in order to work! Try and see it from her point of view so that any discussion is balanced. If you see only your own point of view then you may just sound selfish.
The aim of your discussion should be:
- To agree on a parenting style/routine that you will both stick to
- To discuss a fair share of night-time parenting based on you both getting a reasonable amount of sleep.
- Get your son sleeping through the night!
Perhaps begin by saying:
We do need to talk about [son] sleeping through the night. What do we need to do to get him sleeping through?
See what your wife's opinions are. It does seem that she already subscribes at least to the idea of not giving him attention in order to teach him to comfort himself. But is she already putting that into practice? Did she give up because you picked him up when he cried?
Avoid blaming each other, but focus on moving forward - what do you both have to do now to work together and correct this before it is too late*?
(*most parent-led methodologies involve teaching children to comfort themselves during daytime naps - for example making them nap in the bed they sleep in at night, letting them cry for a time, and if they don't stop crying only comforting them silently by gently putting a hand on them for example, never picking them up. At 2 years old you will have the difficulty that he will probably be standing up in his cot/bed already - but don't give up! There are books out there that help with all situations at all ages! And see the Parenting SE site for further discussions!)
