This happened to me (it kind of long hang in there)
I know what you are going through Bro, as this happened to me.
About 2 years ago, we were having a x-mas party at our house and my wife's (single) best friend invited these two (single) guys she worked with, to the party, one of whom she wanted to hook up with. I guess the guys figured that friends share, and the buddy had a chance at hooking up with my wife since we were going through a rough time at the moment ... blah, blah, blah. I am normally a pretty easy going guy, which can be seen as weak, but I saw what he was doing, although my wife didn't think he was doing anything wrong as she didn't say anything to him about it. and remember this is all going on in my own house. well I saw them talking in the formal living room with no one else around. I walked up to them and made some small talk like I was just another partier there drinking up the booze and said, Hey, this is a really kickin' party, you guys having a good time? blah blah blah... they said yea this is a killer party... some really hot women here.... and I said yea espeically that red head in the black dress... and they said holy shit man she is smokin blah blah blah (the whole time I about to break a blood vessel.... 10 years as a Marine Drill Instructor did nothing to ease the rage factor then mix in gear.... shake liberally and stand back) well I then said.... that hot piece of ass is actually my wife...and you are in my house, so we can handle this two ways.... you can tell everyone that you going to call it an early night and go somewhere else under your own power, or you can leave with my help but one way or the other you are done for the night the only choice is either with or without pain. They immediately said hey were sorry they didn't mean to be disrepectful blah blah blah... and they would leave. I said and one more thing..... If I ever catch or even hear of you getting near her again.... I am going to do to you what you want to do to her .... are we clear... and they said yea no problem. Haven't seen or heard from them since.... and my wife was cool about it, I think after 10 years of marriage she wanted to see if I thought she was worth the effort or would I just "take it".
Much like in the wild....... there is one lion in the pride and he gets all the play... until another one thinks he can kick his ass and take it away.... the one left at the end wins. Fuck all that new age mamby pamby bullshit most guys understand one thing real clear. period.