If a man is head of household and he can prove his wife had an affair, can a man get out of paying alimony?

No you can't without proving that this other man is supporting your wife, which will usually end up costing you more legal fees than just paying the alimony. The laws vary in different states, but in general judges don't like changing anything beyond what they consider a normal divorce. Alimony nowadays is not what you see in the movies, it's based on how much your wife makes compared to you and only lasts a couple of years if that. Judges see it as sort of a temporary "unemployment" check to buy your spouse some time to find a job or adjust her lifestyle. Never agree to Alimony that could be extended or agree to pay your ex-wife health's insurance since your employer can drop her as soon as you are divorced forcing you to pay COBRA for her.

At any rate be careful with attorneys that over-promise. The only guarantee of going to court is a big legal bill. When it goes to a judge even the best attorney can't change the outcome very much in typical cases.

Talk to a lawyer, but from what I understand, infidelity is grounds for divorce and will make a big difference in how the household money is split up.

They're unrelated issues. Adultery is one of the classic grounds for divorce. That is, proving adultery is a way to get the divorce. Once it's decided that you may get the divorce at all, the proceedings move into the stage of the settlement, including alimony. For that part, all the vitriol of whether you can be divorced is in the past, so far as the courts are concerned. Emotionally people tie the two together. Legally they aren't connected.

Most states are "no fault". The reason for the divorce has little, if any, bearing on how the assets are divided.

Not without a lawyer

And you think laws are the same all over the world. Ok then.

How is anyone supposed to answer your question if you don't even say where you are?

no

Nope, the legal system will **** you.

Alimony isn't all that often awarded anymore. But yes, that would help.

No, of course not.

Lawyer, you can talk to one without paying them. Call a couple of them, ask questions.