Husband needs space? What should I do?

So I met my husband since I was 13yrs old. We’ve been married for 12 yrs with a 10yr old son. He works out of town and this is the longest he has been out ( 4 months). For the last month out we’ve been having serious fighting over the phone /he keeps putting his friends and everyone else before me- I even took his clothing out and dropped it off at his moms. He came home today- and said “this may sound stupid but I need space” letting me know that he doesn’t want a relationship. He has never made me doubt about him ,but this past month he lied and I found out. Is he cheating or just needs space . What should I do.