Praise be to Allah (The Glorified and Exalted).
You may live with your wife and the child. As long as the child knows you are not his biological parent, then it is OKAY.
You live in a secular society, in which a child around the teenage years, becomes interested in learning the purpose of life and Who is God. As long as you practice Islam and perform your prayers in the home and may be seen by your wife or child, have good Islamic manners with your wife and child, and hang some Islamic stuff in your home, such as a picture of the Kabah in Makkah, or Arabic calligraphy such as "Bismillah" (In the name of Allah); this may spark the interest of your son to learn about Islam. He may then read an English translation of the Qur'an or watch lectures when he gets older, and it will become obvious to him that Islam is the correct religion to follow. It is okay if he reads the bible, or learns about christianity, you cannot stop it as long as your wife insists on remaining christian. As long as you remain Muslim, both your wife and especially the child will have some connection with the religion and may eventually convert. Don't be in haste. Ask Allah (The Glorified) to guide the rest of your family.
Start associating with the local Muslim community, by converting in the local masjid (mosque) so you can be greeted and make friends with the other Muslims. Talk to some of the brothers about your situation and invite them and their wives and children over sometimes for a barbeque or dinner and allow your child to play with their children. This way your wife and child may make friends with Muslims and they will become more connected with Muslims.
The following websites are helping in learning about Islam. Remember, give your wife some time, if she is extremely unwilling to even speak about religion. If she is more open, then perhaps sometimes over a conversation alone, you may speak about monotheism in Islam (the description of Allah), etc.
1)
http://www.islamreligion.com/
2)
http://thedeenshow.com/show.php?action=guest&id=9
3)
http://www.youtube.com/user/khalifah...g?blend=1&ob=4