Stay or go 16 years

Im try and make this short. I have been in a 16-year relationship with my kids' father we have kids together 13,7, and 3. Since being in a relationship I haven't been happy at all I have tried many times to fix things in different ways. To sum up, our problems are we don't go on dates at all he says cause we don't have a sitter, our Communication is bad, we don't spend any time together we are always in separate rooms, we don't have sex. We are like friends with kids there is nothing between us but our kids a very unhappy relationships I believe for both. A part of me wants to fix it the other part wants to walk away. I don't know what to do. Need advice