Go for the best settlement for you, no matter what. None of my clients have ever come back years later and said they wished they were more generous with their ex. But it sure is common for them to come back and try to undo their prior generosity.
About you paying alimony, even in no fault jurisdictions, it is a rare judge that will award full alimony to an actively cheating spouse. A good lawyer will know the tendencies of the potential judges, have a few tricks to help steer where the case will go, and know how and when to bring up the fact that the person seeking so much support is the one driving the divorce and cheating.
Here's a funny anecdote for you - I know an attorney who had a case before a notorious 'man-hater' judge and his BH client was facing every other weekend custody while paying over 2/3 of his paycheck to his actively cheating WW. His client got wind that his WW was going to the Caribbean, and so my friend slowed down the proceedings until after they went, and then he pieced together the financials showing that his client basically paid for WW and OM's Caribbean vacation while his WW was pleading poverty for their kids. In the next appearance he switched the narrative for the judge from 'BH vs wife and kids' to 'family vs OM'. 1 month later his client had primary custody and no support payment!
