Please Help

my husband and I have been married almost 2 years now and have an 8 month old daughter. He's been experiencing alot of medical issues this year including ketoacidosis, pancreatitis, pinched sciatic, and a diabetic ulcer. because of this, he's been out of work for the past month (has a job, just medically can't do it) and he really can't get around to help me with taking care of the baby. while caring for him and waiting for him to go back to work, I've been primary caregiver for our daughter, working full time plus OT to make up for his lost wages, doing all the housework and cooking, and organizing everything for our move next month. mentally and physically I'm exhausted and I don't think he gets that. He's always going on about how tired he is, but I honestly can't feel sympathetic about that because he's home all day resting while I'm busting my ass. I don't get to sleep in ever because baby is up early and I'm the only one that can chase after her. He helps how he can, but it's limited at the moment.

The other day I came home and he left his phone open. I wasn't going through it (I feel that's a bullshit move) but it was open to where you see all the apps, and I noticed Tindr was on there. I said fuck it and opened that app and he has been messaging 4 girls, one of which he's been talking to for over a month. I read the convos and its all just basic chatting like "how's your day, any plans for the weekend" no sexting or anything like that. I asked him about it and he tried covering up with a lie. When I called him out on it he told me that he's been just talking with them while he's bored at home during the day and that this started while he was in the hospital last month. I told him that I forgive him, but to never let this happen again or he could go back to his moms house.

Personally, I feel rejected, ugly, and just like a failure as a wife. I feel stupid that he did this to me, and I feel like I'm overreacting or maybe underreacting. I don't want to divorce him, and I won't over this, but I'm afraid that I'll have to if this happens again. I love him and I'll do anything for him, but I just feel like I'm not enough for him because of this. I'm overweight and I feel like that's the cause of him doing this and hardly ever wanting to have sex. Ever since we got married, we've only had sex once every week or two if that. With these medical conditions of his it's even dwindled to once every few months. I feel that all of this stems from me being a fatass. Again, I'm not going to divorce him over this, but I would like some insight. Anything really as I have nobody I can talk to about this.