It appears that you stand to receive a valuable benefit as an LPR in the U.S. It is true that some employers do not keep their end of the contractual obligation thus leaving you with very few choices:
1. Terminate the employment,
2. Lose the LPR benefit, as a result upon loss of the employment,
3. Attempt to find a similar position under the circumstances.
In my opinion, the matter of filing separately or jointly lies exclusively with the married couple and has no bearing on the nature of your relationship. You seem to comply with all requirements to the best of your ability. I do not see any arising issue with that situation as long as you have other proofs of your bona fide relationship.
Avvo has a tremendously helpful database of good attorneys practicing in every area of law. You may use the section "find a lawyer" above to find, research and compare an attorney that may assist you in your case in Pennsylvania.
You need to ask for clarification of that statement from the counsel of record who prepares your application for that country.
In terms of the criminal history in the United States, assuming that was the only criminal episode on your record, if the question is "have you ever been convicted" , the legal answer is clearly NO.
Now, pay attention, if the legal answer is worded in a broader format, such as " have you ever been arrested, charged, cited, prosecuted etc. with any offense that did...
Any criminal offense, even a minor charge like yours, is worth fighting for. Why? Because in perspective a poorly adjudicated case like that will create a lasting negative effect of your future employability at a reputable place and diminished ability to pursue your educational goals.
I suggest retaining a local criminal counsel.
You may be charged, and if you do, assert your right to a counsel at once verbally, remain calm, collected and polite and do not make any admissions, clarifications or confessions against your interests. Better yet, discuss your recent development with a good local counsel in case this escalates any further so you will be prepared.
Calm down, the case will not be decided on Avvo. You want a fair resolution of this case and a reasonably positive outcome given your present criminal charge. Select a licensed attorney in your area and meet with that professional to discuss the case's details and legal strategy to lessen the impact of that situation on your future.
Any person within the United States regardless of the status must file an IRS return for all means of derived income in the U.S. As you may imagine, for any prospective immigration benefits one must present the prior compliance with the tax filings.