You obviously can ask him to leave, although he won't have to. In terms of filing for divorce, you can try and do it on your own by utilizing the NY Unified Court System's website, which has the forms, or hire an attorney.
Many attorneys (like me) offer free consultations. Feel free to get in touch to discuss your situation further.
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You should consider consulting local counsel however if you move out, it is unlikely you will be able to move back in without causing an issue.
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