I've not posted on MN before but really had to because so much of what you describe - I've been there. (I'm going to have to change my ID after this!)
My long term partner and I went through a spell of no-sex that lasted at least 5 years - no kidding. It dried up slowly but started out with the type of thing you describe, me feeling repulsed, bored, just wanting it over and done with, dreading to go to bed at night in case he tried it on. I couldn't leave him because he is wonderful man, good friend, and totally supportive of me my work etc - I knew most other men would demand I spent less time working and more time at home. So it was 'easy' to stay with him even though I was sure it would have to come to an end one day.
We both got drunk on a holiday and sex started again. It wasn't fireworks but I was so relieved to join the land of 'normal' again I decided to just keep my mouth shut, resign myself to 'no sparks' and be glad I had a good man.
This is not what has happened. I saw him suddenly with different eyes because he was, unlike me, utterly nervous about sex again and it made me want to cry to see his anxiety and concern for ME over himself. I realised how I had dented his sense of security as a man by revealing my 'sexual disinterest' to him over the years. My talk of need for toys, Ann Summers stuff etc to 'try get things going' made things so much worse for him because I was essentially telling him he was rubbish in bed but without the other talk about why it had got there. Sadly, the more insecure he got, the more careful and 'safe' the sex got and turned into a cycle that got worse and worse until we stopped touching each other at all.
I also realised that the one thing that I counted as a plus with him - the fact he gave me time to pursue my career, made no demands on me, was happy to accept the conditions as they came - was also one thing that made me respect him less. I'd describe him as a 'nice guy' to others, but I had internalised him in my head as a 'doormat' - and that was what had knocked my sexual interest in him.
I feel very different know. I love him with all my heart - I see how incredible he has been all these years. I feel like I am so lucky to have caught a break. Had he left me - and he was well within his rights too - I wouldn't have what I have now. I sometimes find myself just looking at him and thinking how damn lucky I am, how amazing he is, and I get these rushes of love that I NEVER had in other relationshiops with so-called 'sexier' men.
Truth - Sex is not 'fireworks' like when you first meet but it is so loving and wonderful and from what I understand with friends, that's the way it gets after years together. I can HONESTLY say the thought of having sex with anyone else totally repulses me now. I also know full well that an assertive confident go-getting James Bond type of man who wouldn't tolerate nonsense from me would also end in tears - my tears.
I know you're not me and everyone is different, but I guess it concerns me that you have SO SO much to lose if you get this wrong. I'd encourage you to go for couple counselling and try figure it out - it may not be sex-toys that you need, but for the two of you to reconnect on a deep level and maybe (if he's feeling like I think my dh was) for him to feel he can trust you on that level again. In my experience, deep profound love is so much more bonding than sex. Also, in my experience, the problems with sex are not to do with 'sex' but with the relationship between people.
On the other guy - who I think is a bit irrelevant in all this really - MrsHappy makes a very good point. Leopards don't change their spots. I agree with her that if he's committment phobic you're the most attractive type to him. Bottom line is the guy you're lusting over is still EXACTLY THE SAME GUY who dumped you and devastated you no matter what you tell yourself now. He will do it again. In fact, I'd like to slap him for even daring to try rekindle things with you when you have so much to lose - if he cared about you, he'd be yearning for things to come right for you and your three kids instead of messing with it.
I'm not judging you babe (I am judging the other guy though!). It's hard, I know. But be really really careful. I hope things come right for you and wish you the very best.
Sorry long post - you hit a very old nerve with me xx