My heart goes out to you, but your ex didn't take everything. Of course our kids are a great big chunk of our lives, including the sweat and tears we invest in our relationship, but you've mentioned some things that let me know all wasn't lost. You found love again and you're looking to educate yourself more.
I don't always have faith in our legal system (far from it) but I do know there is power in the ink pen and an orderly approach. Document your own efforts and be as thorough as possible with dates and accomplishments on your part to better yourself and include your boys in your future. I don't know the circumstances of which you lost your children, but I would suggest going to any "social service"-oriented classes about parenting to appease the system BEFORE you attempt to get your children back. Even if you're only wanting at this time to keep them with the grandparents, getting them back may be your ultimate goal and any thing you do now positively, will help you and the boys in the future.
Regardless of the case: You are allowed visitation and you can appeal to courts (without a lawyer if you do your homework, or seek free legal counsel if money is an issue). Be clear in your appeal for the ex and his new wife not to take the children, stating that this would further limit your time with your boys and your right to see them. Use your legal rights, not your emotions to address the issue. No name calling and emotional outbursts will be in your favor if you pursue this. Do not cast him as the "ex from hell". It will only appear as an angry remark and work against you. Your focus is your boys.
Things will continue to get better if you use your head and take careful steps to get your boys or at least maintain them with the grandparents. Do not inform the ex of what you're doing, (it may be tempting to gloat, but don't do it) let him be served papers--that is if he actually keeps his word about trying to take them. Communicate through an advocate/lawyer, etc. Meanwhile communicate through cards, mail, and pictures to show your willingness to have a relationship despite the circumstance. I hope this helps.