Separation and not coping

Hi have read this page for a while and wanted to ask but to scared but here goes..please be kind

Background we had a good marriage over 20 years but decided to invest in husbands business a few years ago as a partner he had worked there for 10 years and thought would be great investment and set us up. Long story owner of business made all excuses my husband wasnt performing doing job correctly and he took all the money. Kicked hubby out of business. We were devastated we nearly lost house. We found out owner was doing drugs, having affairs etc obviously it wasn't great for our family we have 4 kids. My husbands starting drinking alot not coming home was drinking with mates around corner trying to keep it together. We were both unhappy. One night he said what are we doing we aren't happy we decided to separate but live together in separate rooms in house and told children. I tried to get couselling he wouldn't talk to stranger said he would only talk to me. We needed help. Tried to get kids to go to counselling they wouldn't. My older daughter took herself to counselling. Going forward i thought we would fix things i thought it was a temporary thing. He eventually went on line on POF met some one a long way away. Kids met her once at his place for dinner she didnt speak to them at all and kids said it was very awkward and couldn't wait to come home. The kids made me tell him they felt very uncomfortable with her and as she made no effort they didnt want to do that again. They haven't see her since. Started disappearing for a few nights a week and kids & I didnt know where he was but i obviously figured it out to meet her and staying every 2nd weekend. I was left with kids and used house like a hotel. Paid bills and mortgage just lived his own life. He moved out last year close by us to see kids but sees kids 2-3 hours a week only for dinner and rest time his on his own doing what he wants. Kids don't want to stay there as small, no internet or foxtel and dad doesn't do anything but watch tv with them. When he left he left me with debt from council rates which he didnt pay for over a year, water bill which hadn't been paid either. I'm now paying these bills off. I'm getting child support which covers mortgage only. He now won't respond to me via email or text blocked me on phone as he said doesnt want to deal with me will deal with kids only. I'm working full time but feel very sad we didnt fix things, that he met someone else and moved on and not particuarly interested in seeing children.I pretty much have kids 24/7 which is fine I'd rather them be where they are wanted and loved with me. I've lost two friends as they were mutual friends of ours but sided with him and see them now as a couple. I'm on anti depressants at the moment had counselling and have supportive friends and family. Just feeling sad all the time i see other couples together and makes me sad and at my age not sure i will meet anyone else. I'm not interested in online dating. I'm exercising and trying to be positive but get sad all the time and miss what we had.