WIBTAH if I sign away the right to my kids?

I am a single mom of two wonderful boys. I honestly feel lucky how they turned out. They're both giants for their age, but so kind and sweet. I share custody with my ex-husband (Drew). We've been divorced for five years now. Every year, it's becoming harder and harder to support us. It's all my fault and I don't know what else to do.

I was with my husband for 14 years, married for eleven. We got married relatively young and had kids soon after. I remember the last couple of years feeling trapped in my marriage. Life became very monotonous and boring. I had feeling of resentment for "missing out" on my youth and not being able to join my friends on night out. Me and Drew also grew apart. We neglected "us." Or maybe I neglected him and he stopped trying. Who knows, but it certainly wasn't exciting. All these feelings build up in me until one day I told him that I wanted a divorce. I couldn't imagine living another month like this, let alone the rest of our lives.

He pleaded for us to try to work it out, maybe go away somewhere, but once I said it out loud, I felt like I had a purpose. Once he realized there was no going back, he said let's split amicably. I'm not proud of the way I acted back then. I got a lawyer and went through with it. At the end, we split the assets, including proceeds from sale of the house evenly and shared custody of the kids. Just like he offered. I got child support, a whopping $19 a month more than he offered. No alimony and a pile of attorney's fees.

Still, the first few months were great. I had a good support system, I had plenty of babysitting options as everyone was trying to be supportive. Friends were taking me to places, taking my mind off of things, making up for lost time. But after a while, the help dried up. Everyone became busy with their own problems. It was much harder making ends meet with a single income. The apartment I rented was a big downgrade from our house. I'm tired all the time. Whenever my ex had them, I would just end up watching TV and just lying around instead of going out. I've had one semi-serious relationship. It's extremely hard to meet men who are serious about building something. Drew became very distant. I heard of coparenting situations where exes get along great. Not Drew. He never responds to my texts, only talks about the kids.

As they get older, they're enrolled in three sports each, there's more and more expenses. I can't afford to buy them the stuff they need, even half of it. Finally, last month I talked to Drew about it. Asked him to be more involved in their life, especially financially. Drew flat out refused to contribute a cent more to them over the child support payment and what he pays when he has them. I explained that I simply can't keep up with all of it. He finally said, they're welcome to stay with him full time. He'll cover all their expenses and be wholly responsible for them. If I gave him full custody and signed away my rights. He said you can still see them whenever you like, you'll just have no legal rights. I know the boys would love to live with dad. They're too nice to say it, but it's obvious dad is the favorite parent. AITA for even considering. WIBTA for going through with it?

Edit: To answer some questions people have, yes I have tried to talk to Drew about modifying the custody agreement. He refused any change to our current arrangement unless it's signing away my rights. I talked to Drew about more child support and told him I'd go to court. He said go ahead, you'll end up with less. After last time, I'm very hesitant to do it. I don't want to tell the kids do drop an activity. They love it and I don't want to tell them I can't afford it.