Tired of crying every day

After 15 yrs my s/o found love somewhere else and walked away from the family 😓😓 it’s been messy and full of deceit he still comes by for our children but he also still has sex with me I know it’s wrong and stupid but how do I throw away 15 yrs of emotions?? I know when he leaves he’s going back to her and the life he actually wants😓😓 I need advice ladies and not just saying leave because that’s the hardest part