Every one tries to make their career at your age but that does not mean that you run away from your other responsibilities. To give time to your wife and family is your moral responsibility. Try to balance your time between work and family. “Once I will settle down” that in fact never happens in life, life is always on.
Your wife is emotionally pressurizing you by proposing separation for couple of years. Try to talk to her sympathetically and be always available to her mentally as well as physically (do not put time as an excuse, manage your time any how).Never ever become physically violent as it is most traumatizing for any person. (I think you are frustrated because of situation and taking it out physically). This will only worsen your problem. At the same time I will like to advise you not to succumb emotional blackmailing because that will create new issues in your life, offer her practical solution instead.And even after doing this,if she insists sepration then give it a try if you can.sometimes absence of person makes you to realise certain things better.