Thank you for bringing your question to Just Answer!
Trying to blend families is one of the hardest challenges of modern life. I'm glad to see the two of you are getting some counseling. I have a fair amount of experience in this area (relationships with children from previous marriages) and you may be surprised at my take on this.
It makes sense that his daughters are having a hard time adjusting to the change--going away to college is both exciting and frightening. This is a rite of passage that makes them asking for their parents to be there very understandable. They are probably being somewhat protective of their mother,as well, as she's alone at the moment. Texting is a way of life with college age kids...if it bothers you, ask him to turn off his phone during intimate moments together.
If would be almost impossible for him to be able to be an excellent co-parent and not have contact with his ex. He cannot control her actions, but his responses seem very appropriate: he just kept mowing the lawn, etc. He does seem to have a good sense of boundaries with her.
Expecting to go to college activities when the ex-wife must be present may not be your best response. Expecting to be invited to Christmas morning at the ex-wife's house may also be unrealistic. Would you feel comfortable entertaining her on Christmas morning? There are certain times when you will be an outsider in that family system--birthdays, holidays, momentous occasions like first day of college, the girls' weddings.
I fear that your taking these things personally, rather than recognize that you will most likely never (even if the two of you marry) be a full player in that family constellation, will create conflict where there doesn't need to be any. Make wonderful plans for yourself on the days when he must interact with the ex--be with friends, go to a spa, anything that will give you a rich experience that you'll enjoy.
He sounds like a very responsible, respectful man. Don't focus on what you can't do with him (activities with daughters) but instead on all the rest of the time you have together. You can be sure that the ex wife is much more jealous of the time you have with him than you could ever imagine. Try to have some compassion for the loss and grief she must be feeling at this point.--she lost him, and now she's losing her daughters to college. Her nest is very empty. Yours is full--you have him and your boys.
You'll be much happier if you can get to a place where you can accept the fact that his life is compartmentalized, recognize that he has a good sense of boundaries and enjoy your time together rather than focusing on a day here or there that he's with them.