are macbeth and lady macbeth co-dependant
Yes, both Macbeth and Lady Macbeth are dependant on each other.
Macbeth is a "worthy gentleman" (1.2) in the beginning. He has a hidden wish to gain control over the throne, but lacks the depth of zeal. He needs an instigator to win his game. About his nature, Lady Macbeth's utters: "yet do I fear thy nature, /It is too full o' th' milk of kindness...What thou wouldst highly, / That wouldst thou holily" (1.5). This spur would be his wife's motivation without which he would not be able to overcome his dilemma.
Lady Macbeth is greedy. She has also the desire to become queen. In order to achieve her goal, she has to stimulate her husband, and use his masculine power which is quite essential to perform the continual murders.
Definitely, the husband and the wife are collaborator, and what they execute, are put to taste their consequences together.