What does Genesis 38:26 mean?Judah realizes that he has been caught in a trap, laid for him by Tamar (Genesis 38:14–19). More than that, though, he realizes he is not merely guilty, but even more guilty than she is. He admits his guilt in not following through on his commitment to marry his third son to Tamar (Genesis 38:11). Tamar's desperate move was inspired by being a childless widow; Judah's broken promise left her with little hope.
It's important to note that Judah does not say Tamar is guiltless. Tamar's actions aren't justified, in any sense, but Judah fully realizes his role in creating the situation. And, of course, he's at least guilty of the basic sin for which he was just demanding Tamar suffer a death sentence. In essence, Judah says that whatever Tamar has done, his own sin is worse. He, too, is guilty of sexual immorality, as well as lying and abandoning a widow.
Scripture gives no details on the relationship between Judah and Tamar from this point forward. All we know is that Judah did not again sleep with her: there was no continued sexual relationship. Whether she was taken in as a full-fledged wife, or merely cared for in the household, we are not told. For all intents and purposes, Judah has taken on the "levirate" responsibility (Deuteronomy 25:5–6) which should have fallen to his son (Genesis 38:11).
Tamar's plan was extremely dangerous. She was fortunate, in a sense, to have become pregnant and had the opportunity to prove Judah's involvement. Once again, Israel's early history is marked by grand deception and startling revelations (Genesis 27:34–35; 29:21–27; 37:23–28).