All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger.
First of all, we blame you for divorcing your wife and separating from her all this long period and then having sexual intercourse with her after she became irrevocably divorced (with minor separation) from you, and now you ask about the ruling of this divorce and that sexual intercourse. You should have asked about the ruling of that before having sexual intercourse with her.
Moreover, you should know that anger does not prevent divorce from taking place because, in most cases, divorce happens at the time of anger. Indeed, the scholars divided divorce at the time of anger into three cases: so in some cases divorce takes place and in other cases, it does not. For more benefit on these cases, please refer to Fatwa 121374.
In fact, you are more aware of yourself when you uttered divorce when you were angry. If we presume that divorce had taken place, then you were sinful because of having sexual intercourse with your wife after her waiting period had expired, so you are obliged to repent.
Now, if you want to marry her again, you may do so but with a new contract. However, according to the view of some scholars you are obliged to make sure that she is not pregnant [this is either by her observing one menstruation or giving birth to a child] before you marry her again.
For more benefit, please refer to Fatwa 82541.
Allaah Knows best.