Why does Iago continue to “follow” Othello in line 44?

Iago has already made it perfectly clear just how much he hates Othello. Yet he still follows him. The reason he gives is that it will allow him the opportunity to carry out his revenge more effectively. Iago figures that it's much better to destroy someone from the inside than from the outside, as it were. Hiding behind a mask of loyalty will lull Othello into a false sense of security, making him more vulnerable to Iago's vile machinations. Iago will play the part of loyal servant to perfection, while at the same time, destroying his master.
But, according to Iago, there are two kinds of servants. There are those who display complete loyalty to their masters for the whole of their lives, yet end up with nothing. Frankly, he thinks they are stupid and ought to be whipped. Then, there are those servants who appear to be devoted but are really acting in their own interests, out for what they can get. Iago makes it abundantly clear to Roderigo that he is just such a servant:

Others there are Who, trimmed in forms and visages of duty, Keep yet their hearts attending on themselves And, throwing but shows of service on their lords, Do well thrive by them. And when they have lined their coats, Do themselves homage. (Act I, Scene I)