Under what circumstances did you leave this man's employment? From what you are saying, this was not a simple lack of work separation, as you said, he appealed your claim twice, and yet you still received benefits. From this I am guessing that he probably terminated you and there was determined not to be sufficient misconduct reason to terminate to keep you from drawing benefits.
You will need to report this offer of work immediately to your unemployment system. Call it in and talk to a living human being before you certify for this week's claim. Ask them specifically how you should fill out the certification. Explain to them what you have told me, how you have been called and offered a rehire at approximately half the former salary by this person who (?what? )fired you before? Tell them how he has been heard bragging that he will stop your drawing by offering you another job.
They will have to make a decision on this, it will probably delay your pay for these next couple of weeks. But rest assured that even if you did not report you had been offered the job, he'd call them and tell them he had offered you the job, so it would be fraud and would be discovered by them if you don't report it.
If you had been laid off due to lack of work, and the employer was fine with your receiving benefits because he didn't have the work for you to do anymore, and then now he has more work and he's reoffering you your old job back, that would probably be considered a legitimate job offer, and you'd have to take it or your benefits would stop.
But if the employer has terminated someone or they have quit for what has been determined to be a valid work related reason, and their benefits have been approved through appeal, the employer cannot then cancel the benefits by offering to rehire the person. That's what the decision they'll make will say about this offer of work. The relationship between the two parties has been severed. Believe me, many employers have thought of this little dodge when the former employee has been approved to draw benefits.
It would be totally dumb of you to go back to this job, of course, as if you did he's going to simply make your life a living hell until you are forced to quit or until he can think of a better reason to fire you.
But if you've been drawing for a year and a half, you're getting awfully awfully close to running flat out of unemployment benefits anyway, it's not really going to be a big deal. You will need another job somewhere very quickly.