Does the married poly man that you're seeing have children? It can be hard to have conversations with people on any kind of regular ongoing basis when you're trying to meet the needs of children at home. Also around Christmas time there are a lot of family obligations and it can be very hard to get to a phone or a computer to stay in touch with other loves (especially if you're not out to extended family). If you're having a good time when you're with him I wouldn't go breaking it off right away. Although being specific about what you need from him in terms of communication might be a good idea.
You might need to compromise with him on how much communication he is able to give. He might not be able to give more than a short daily check in, but at least that's a good start.
As far as the mono girl who wants you to be mono with her you probably both need time and space before trying to start a friendship. Otherwise it's just too easy to fall into old patterns, especially if you both like being physical with each other.
The third boy who's gf dumped you (vetoed?) yeah, don't get involved with him again. That's just going to be all kinds of drama for you. It sounds to me like his gf has a lot of work to do before she's ready to take on the whole poly thing.
Everything will be ok in the end. If it's not ok it's not the end.