Unhappy

My husband and i recently had our 5 year anniversary as a married couple.but i am unhappy for like 3 years now. Been trying to talk about it with him and nothings changed. I recently had an affair with my coworker/friend. He ended things with me because his girlfriend found out and threatened him that he wont see their kid again if he chose me. Ive just been trying to keep myself busy all the time so i dont have any down time and feel sad and depressed. My kids are 3 years old and 8months old twins. And i am just losing it at home and plus the stress at work working full time. I dont feel like my husbands wife. I feel more like his helper to look after the kids and the house. I dont know what else to do. Been thinking about going to couples therapy but i know my husband wont want to go and we dont have anybody to leave the kids with if ever we do go. And i dont want him to find out about the affair. He has questioned me a lot of times but i lie everytime. I think im going crazy