Marrying a widow as a second wife

I hope respected mufti sb is in best of Imaan and health.This is a very awkward question for me to ask but I am stuck in this dilemma. However I am trying my best not to violate the laws of shariah and Mufti sahebs opinion and advice is very important for me and will inshaAllah aid me in this.Alhumdulillah I am a married man with children and my marriage is running perfect. I have no problem with my wife and we are very happy with each other. Just recently another sister that I’ve got to know has asked me if I can marry her. She is a widow with a child. Now obviously she is someone who has nobody really to help her in certain things which only a husband can do for her and wants to marry. She is also okay and doesn’t mind that I am already married. However I have a few questions regarding this as I do not want to marry her with the intention of helping her and doing a good act then falling into sin. Obviously majority of men wouldn’t mind a second wife but I am perfectly happy not to go ahead with the second marriage if it is or can be islamically incorrect in any way.
Is it permissible to get married to a second wife without informing my first wife?