Getting Laid

I'm Brian 35 married 4 children, after our last child was born. My wife Ruth 33 went off sex and I very rarely get laid. She knows it is a problem and is seeking help, but in the mean time I don't get sex from her unless she gets drunk. She rarely drinks and I enjoy when she lets me. Post natal depression is what her doctor calls it, I wish he would find a cure for her. Last November my widowed mother Robyn 53 moved in with us, mainly to help Ruth with the children. Then a week later Ruth went in to hospital and was gone a week, she had stomach cramps and had surgery. Meanwhile I was home with the children and Robyn, the second night Robyn caught me masturbating. She said Can't go a couple of nights without Ruth. I answered I haven't had sex with Ruth for nearly a year, she has post natal depression. This is how I cope. Well I better help you out she replied and she took hold of my cock and started to stroke it. Then she started to suck it and she soon had me blow my load onto her cheek. I was shocked at first, but soon didn't care. I was enjoying it too much, after she said Anytime you need help let me know. I said Okay and an hour later I was going for a shower. As I passed Robyn I asked If she would wash my back like Ruth use to do. At first I thought she would say No, but she said Alright you can wash mine. In the shower she washed my back and I hers and I got a hard on an asked If she would let me fuck her. She said You might as well and we had sex in the shower and spent the night together. Since then I've been getting regular sex from her, even after Ruth returned home from hospital. Robyn started massaging Ruth to ease tension, she hope to help Ruth thru her post natal depression. I came home last Thursday for lunch and found in bed together, with Robyn licking Ruth's vagina. Robyn told to take over the licking and she sat on Ruth's face and had her vagina licked. I had sex with Ruth and late on after I finished work that day. Robyn told us we should have threesome that night and at first Ruth wasn't keen. She came around to the idea, since then the 3 of us sleep together every night. I'm still getting more sex from my mother Robyn than Ruth, but at least she joins in.