help!! caught between my husband and son 😢

I have a 14yr old son and he had been wanting a cell phone (like any other teenager) for about 2 yrs. my husband (my sons step father) has always refused to let my some have a cell phone. I allowed my son to get a cell phone behind my husbands back because I felt bad for my son. My husband found out and this has happened about 3 or 4 times before but my son would always take the blame for it to spare me the arguments with my husband. I feel horrible for that and feel like the worst parent in the world. Well tonight my husband found out I did know about my son having a phone and now I feel so bad because my son feels guilty for my husband saying that it could lead to is separating. I don't know what to do. Please help. I need some advice.