Is it a sex crime if my ex spouse diffuses our sextape on the Internet?

Wow. This is a very good question. You have to consider that a lot of people have become famous from the diffusion of sextapes – to wit: Paris Hilton and Kim Kardashian. So it is not clear that the mere diffusion of the tape is a “crime.” Sex crimes are serious and it requires the convicts to register as sex offenders and once that happens a person’s life is over. So it is a very high bar to jump over to prevail on a sex crime charge. And with regard to the diffusion of a sextape that was willingly made by both parties? It becomes even harder to prevail.
How can you prevail? First, you have to show that you did not consent to the making of the tape. Then you would have to show that you did not consent to the diffusion of the tape on the internet. If you were under 18, you can claim it is child pornography which would be easy to get a conviction on but most people who were married would not fit this criterion – although one never knows. If this happens within the context of a case where an order of protection was in place for harassment or abuse, this might be helpful to your cause of action though not necessarily decisive.
For sure, you can sue your ex in Civil court even if you can’t prevail in criminal court. And you can win damages for emotional distress and invasion of privacy – among other torts, I would imagine.
Just as general rule of preaching, however, it is probably best practice not to make any sextapes with anyone – even if it is your husband or wife – given that you never know if you will stay with this person forever or not, or even if someone could find the tape and diffuse it unknowing to your partner. And this is always a defense your partner has. He or she could say that the tape was stolen (even if it wasn’t!) and beat the criminal charge.