Look at it from your husbands point of view. This is a massive change for him to try and absorb. His wife suddenly has all these different desires, that may not be his desires at all. He has his own desires and his own turn ons and up until recently, you both gave each other what you both assumed you wanted. Suddenly you are asking him to flip 360 and go from that, to this new way and just because you are floating in the air, high on these potential new experiences, he might not be at all interested in Dominating/BDSM or the same kinks you are in to.
In other words, just because you found this amazing new thing, doesn't mean he wants it. I feel, when I read your two messages that in this case, you haven't thought about what HE wants. I say this because you say he has "Negative thoughts on it" and he "Keeps making excuses" Has it crossed your mind that maybe he is not interested? He hasn't had that kick to the gut moment of "Oh my GOD, THISSS is amazing" like you have.
So lets say he is only half heartedly into this, which is what I am picking up from the two comments I quoted above, and the fact you are thinking of going to meet a Dom alone because you assume he will say no (This all really sounds like he is not into it, or is nervous, and treading slowly and lightly, not throwing himself into this yet because he doesn't know) It sounds like he is trying for you, to please you, but if it is not his thing??.....
This will end two ways.
1) This lifestyle will SLOWLY grow on him, not at the speed you are hoping for right now, because he isn't as thrilled about this as you are, but if he tries little things and likes them, it may grow on him and he may begin to come into his own.
2) You will resent each other and possible, or probably, grow apart.
You feel that you will begin to resent him if he doesnt go along with your new plans to meet this Dom and push fast ahead into your new lifestyle. It is also entirely possible he will come to resent you too, for not being open and accepting of his feelings about all of this. If he says "no" and you plow ahead with secret meetings with Doms etc, he will resent you too. You feel he is failing you in your new desires, but you are failing him too if you don't listen closely to his desires and feelings
Right now, you are not submissive, and he is not Dominating you. Right now, you are Dominating him and is is submissively and half heartedly trying to oblige.
You are saying you will resent him for not fulfilling your needs and it sounds like you intend, or are at least thinking about, going off and ahead without your husbands involvement (Meeting men online.) this is someone so wrapped up in this new exciting thing that they have not stopped to think about this carefully. You could lose him. However, if you are incompatible and would choose the lifestyle over hubby, then maybe that is the natural progression to this. Some people simply cannot life without these aspects, it is who they are to their core, but trying to beat a square peg into a round hole so that he can meet your needs, may be a step too far for him.
My advise:
Tell hubby everything, not just about the meet with the Dom, but how you feel and stop for one moment and find out how he really feels about it all. Then try to compromise together. Ask him what he needs from you to make this easier. Time? Patience? Advice? (Does he really want advise from some random internet guy? I know that would freak my guy out, he would rather go read or watch videos to learn things) Be careful about meeting random internet men, especially on your own, and don't get blindsided by men on fetlife claiming to be Doms and wanting to offer that advice (What's in it for this Dom, to come spend his time teaching you?) and bear in mind 90% of internet Doms are just random guys who have figured out that if they say they are Doms, they can grab a hold of women new and blindsided by this thrill, tell them they are doms and have you doing all sorts of shit for them, because "They are Dom and you are sub" Just.....be careful with that one. It happens oh so often.
Hope this helps somehow. xxx Deffo speak to him though, and to save your relationship....don't meet this Dom alone, without telling him!