How can you tell when it's time for divorce/separation?

I've been with my husband for 12 years (married for 8yrs). We've had many problems/difficulties in our relationship, but we always managed to keep moving forward. A couple of months ago I started feeling like he's not the man I need. He's gotten lazy, we're always arguing about the tiniest nonsense, we haven't had sex in months, and the last few times we did have sex it was horrible for me (he was done in less than 5mins, we had no connection what so ever). I just feel like I'm done, I've talked to him about it and he says "well you know the options...."

I honestly feel like I'm hanging on for our three children. I try to hide the fact that I'm no longer happy, they have no idea how miserable I truly am.....

Any advice please 🤍